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Arizona State University
1.
Ahlf, Rick.
Autonomic Closure in Reynolds-Averaged Navier-Stokes (RANS)
Simulations of Turbulent Flows.
Degree: Aerospace Engineering, 2017, Arizona State University
URL: http://repository.asu.edu/items/44058 
► Reynolds-averaged Navier-Stokes (RANS) simulation is the industry standard for computing practical turbulent flows – since large eddy simulation (LES) and direct numerical simulation (DNS) require…
(more)
▼ Reynolds-averaged Navier-Stokes (RANS) simulation is
the industry standard for computing practical turbulent flows –
since large eddy simulation (LES) and direct numerical simulation
(DNS) require comparatively massive computational power to simulate
even relatively simple flows. RANS, like LES, requires that a user
specify a “closure model” for the underlying turbulence physics.
However, despite more than 60 years of research into turbulence
modeling, current models remain largely unable to accurately
predict key aspects of the complex turbulent flows frequently
encountered in practical engineering applications. Recently a new
approach, termed “autonomic closure”, has been developed for LES
that avoids the need to specify any prescribed turbulence model.
Autonomic closure is a fully-adaptive, self-optimizing approach to
the closure problem, in which the simulation itself determines the
optimal local, instantaneous relation between any unclosed term and
the simulation variables via solution of a nonlinear, nonparametric
system identification problem. In principle, it should be possible
to extend autonomic closure from LES to RANS simulations, and this
thesis is the initial exploration of such an extension. A RANS
implementation of autonomic closure would have far-reaching impacts
on the ability to simulate practical engineering applications that
involve turbulent flows. This thesis has developed the formal
connection between autonomic closure for LES and its counterpart
for RANS simulations, and provides a priori results from FLUENT
simulations of the turbulent flow over a backward-facing step to
evaluate the performance of an initial implementation of autonomic
closure for RANS. Key aspects of these results lay the groundwork
on which future efforts to extend autonomic closure to RANS
simulations can be based.
Subjects/Keywords: Aerospace engineering; Autonomic Closure; FLUENT; Machine Learning; RANS; Reynolds-Averaged Navier-Stokes; Turbulence
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APA (6th Edition):
Ahlf, R. (2017). Autonomic Closure in Reynolds-Averaged Navier-Stokes (RANS)
Simulations of Turbulent Flows. (Masters Thesis). Arizona State University. Retrieved from http://repository.asu.edu/items/44058
Chicago Manual of Style (16th Edition):
Ahlf, Rick. “Autonomic Closure in Reynolds-Averaged Navier-Stokes (RANS)
Simulations of Turbulent Flows.” 2017. Masters Thesis, Arizona State University. Accessed January 22, 2021.
http://repository.asu.edu/items/44058.
MLA Handbook (7th Edition):
Ahlf, Rick. “Autonomic Closure in Reynolds-Averaged Navier-Stokes (RANS)
Simulations of Turbulent Flows.” 2017. Web. 22 Jan 2021.
Vancouver:
Ahlf R. Autonomic Closure in Reynolds-Averaged Navier-Stokes (RANS)
Simulations of Turbulent Flows. [Internet] [Masters thesis]. Arizona State University; 2017. [cited 2021 Jan 22].
Available from: http://repository.asu.edu/items/44058.
Council of Science Editors:
Ahlf R. Autonomic Closure in Reynolds-Averaged Navier-Stokes (RANS)
Simulations of Turbulent Flows. [Masters Thesis]. Arizona State University; 2017. Available from: http://repository.asu.edu/items/44058
West Virginia University
2.
Pokharel, Ansan.
Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study.
Degree: MS, Mechanical and Aerospace Engineering, 2020, West Virginia University
URL: https://doi.org/10.33915/etd.7671
;
https://researchrepository.wvu.edu/etd/7671
► Modeling of a turbulent two-phase gaseous-solid flow still faces challenges. The present study is devoted to two-phase flow in an annular pipe (hollow cylinder)…
(more)
▼ Modeling of a turbulent two-phase gaseous-solid flow still faces challenges. The present study is devoted to two-phase flow in an annular pipe (hollow cylinder) operating at an elevated pressure of 15 bar and moderate
Reynolds numbers of circa 6 x 10
3. The influence of the various factors – such as the particle loading, the interaction between the phases, and turbulent dispersion – on the flow dynamics is systematically studied by means of the computational simulation employing the ANSYS FLUENT commercial package. To be specific, particle loading with a volumetric fraction of 1.2 % is defined as high particle loading, while the flow with a volumetric fraction of 0.13 % is referred to as low particle loading. In particular, seven various cases for a gas-solid phase flow are investigated:
1) Pure gas flow;
2) Low particle loading two-phase flow with one-way coupling and with turbulence dispersion;
3) Low particle loading two-phase flow with two-way coupling but without turbulence dispersion;
4) Low particle loading two-phase flow with two-way coupling and with turbulence dispersion;
5) High particle loading two-phase flow with one-way coupling and with turbulence dispersion;
6) High particle loading two-phase flow with two-way coupling but without turbulence dispersion;
7) High particle loading two-phase flow with two-way coupling and with turbulence dispersion.
The boundary layer was found to be growing without fluctuations of the turbulent kinetic energy (TKE) for Cases 1, 2, and 5 above. For Case 4, the TKE fluctuations have been identified though appeared not as substantial as in Cases 6 and 7. The author attributes such a difference in the fluctuations to the particle loading. In addition, the onset and development of the flow instability have been observed at a random axial distance in Cases 4, 6, and 7. Such instability is presumably attributed to the two-way coupling with turbulence dispersion in a flow. It is concluded that the particle loading, one-way, or two-way coupling between the phases, and the turbulence dispersion models significantly influence the flow dynamics. The present computational results inspire to perform experimental verification and validation of the simulations, so the simulation results can subsequently be used for the design analysis.
Advisors/Committee Members: V’yacheslav Akkerman, Ismail Celik.
Subjects/Keywords: Staged pressurized oxy-fuel combustion (SPOC); phase coupling; particle loading; turbulence dispersion Reynolds-Averaged Navier-Stokes (RANS) modeling; Mechanical Engineering
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APA (6th Edition):
Pokharel, A. (2020). Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study. (Thesis). West Virginia University. Retrieved from https://doi.org/10.33915/etd.7671 ; https://researchrepository.wvu.edu/etd/7671
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Pokharel, Ansan. “Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study.” 2020. Thesis, West Virginia University. Accessed January 22, 2021.
https://doi.org/10.33915/etd.7671 ; https://researchrepository.wvu.edu/etd/7671.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Pokharel, Ansan. “Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study.” 2020. Web. 22 Jan 2021.
Vancouver:
Pokharel A. Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study. [Internet] [Thesis]. West Virginia University; 2020. [cited 2021 Jan 22].
Available from: https://doi.org/10.33915/etd.7671 ; https://researchrepository.wvu.edu/etd/7671.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Pokharel A. Impact of Particle Injection on Gas Flow at Elevated Pressure: A Numerical Study. [Thesis]. West Virginia University; 2020. Available from: https://doi.org/10.33915/etd.7671 ; https://researchrepository.wvu.edu/etd/7671
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Michigan
3.
Kim, Kunho.
A viscous -inviscid interaction study using complementary RANS equations.
Degree: PhD, Ocean engineering, 2004, University of Michigan
URL: http://hdl.handle.net/2027.42/124098
► A complementary set of RANS equations has been developed for an incompressible fluid flow. The method is based on a decomposition of the velocity vector…
(more)
▼ A complementary set of
RANS equations has been developed for an incompressible fluid flow. The method is based on a decomposition of the velocity vector field into a viscous flow and a potential flow. The decomposition introduces a new complementary velocity and two additional convection terms involving viscous and potential solutions to the conventional
RANS equations. The proposed complementary
RANS equations have been validated for steady laminar and turbulent flows. The laminar flow cases include the flow in a three-dimensional square duct at Re = 790, the flow over a two-dimensional flat plate at Re = 7900, and the flow over a two-dimensional NACA 0010 airfoil at Re = 7900. The turbulent flow cases include the flow over a two-dimensional flat plate at Re = 1.6E6, and the flow over a two-dimensional NACA 0012 airfoil at Re = 2.8E6. The computational results indicate that the smoothness of a potential solution is important to reduce the numerical errors in the evaluation of the two extra terms in the complementary
RANS solver. The feasibility of the new method is shown by the good agreement between the predictions of the complementary
RANS solver (u*-code) and the results from a conventional
RANS solver (u-code) as well as other experimental and numerical data. The u*-code shows less grid-dependency than the u-code, which opens the possibility to save computational time by using less resolved grids.
Advisors/Committee Members: Beck, Robert F. (advisor), Sirviente, Ana I. (advisor).
Subjects/Keywords: Complementary; Duct Flow; Equations; Rans; Reynolds-averaged Navier-stokes; Study; Using; Velocity Decomposition; Viscous-inviscid Interaction
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APA (6th Edition):
Kim, K. (2004). A viscous -inviscid interaction study using complementary RANS equations. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/124098
Chicago Manual of Style (16th Edition):
Kim, Kunho. “A viscous -inviscid interaction study using complementary RANS equations.” 2004. Doctoral Dissertation, University of Michigan. Accessed January 22, 2021.
http://hdl.handle.net/2027.42/124098.
MLA Handbook (7th Edition):
Kim, Kunho. “A viscous -inviscid interaction study using complementary RANS equations.” 2004. Web. 22 Jan 2021.
Vancouver:
Kim K. A viscous -inviscid interaction study using complementary RANS equations. [Internet] [Doctoral dissertation]. University of Michigan; 2004. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/2027.42/124098.
Council of Science Editors:
Kim K. A viscous -inviscid interaction study using complementary RANS equations. [Doctoral Dissertation]. University of Michigan; 2004. Available from: http://hdl.handle.net/2027.42/124098
4.
Kayne, Alexander.
Computational Fluid Dynamics (CFD) Modeling of Mixed Convection Flows in Building Enclosures.
Degree: MA, Mechanical Engineering and Materials Science, 2012, Washington University in St. Louis
URL: https://openscholarship.wustl.edu/etd/740
► In recent years Computational Fluid Dynamics: CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and…
(more)
▼ In recent years Computational Fluid Dynamics: CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the
Reynolds-
Averaged Navier-
Stokes:
RANS)
equations of fluid dynamics. Large Eddy Simulation: LES) or Direct Numerical Simulation: DNS) of
Navier-
Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ
RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements: mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2-D closed vertical cavity, second for forced convection in a 2-D rectangular cavity and the third for mixed convection in a 2-D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-ε two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements: mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are: 1) air flow and heat transfer in a naturally ventilated room and: 2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.
Advisors/Committee Members: Ramesh Agarwal.
Subjects/Keywords: Computational Fluid Dynamics; CFD; RANS; Reynolds Averaged Navier-Stokes Equations; Turbulence Model
…7
2.4.1 Reynolds Averaged Navier-Stokes Equations… …Turbulence Modeling
2.4.1 Reynolds Averaged Navier-Stokes Equations
Direct numerical simulation… …Averaged Navier-Stokes (RANS)
Equations:
Conservation of Mass
∂ ( ρu )… …Averaged NavierStokes (RANS) equations. Because of the relatively low airspeed in each… …averaging Equations (2.1)-(2.5)
transforms them into the well-known Reynolds…
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APA ·
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CSE |
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APA (6th Edition):
Kayne, A. (2012). Computational Fluid Dynamics (CFD) Modeling of Mixed Convection Flows in Building Enclosures. (Thesis). Washington University in St. Louis. Retrieved from https://openscholarship.wustl.edu/etd/740
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Kayne, Alexander. “Computational Fluid Dynamics (CFD) Modeling of Mixed Convection Flows in Building Enclosures.” 2012. Thesis, Washington University in St. Louis. Accessed January 22, 2021.
https://openscholarship.wustl.edu/etd/740.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Kayne, Alexander. “Computational Fluid Dynamics (CFD) Modeling of Mixed Convection Flows in Building Enclosures.” 2012. Web. 22 Jan 2021.
Vancouver:
Kayne A. Computational Fluid Dynamics (CFD) Modeling of Mixed Convection Flows in Building Enclosures. [Internet] [Thesis]. Washington University in St. Louis; 2012. [cited 2021 Jan 22].
Available from: https://openscholarship.wustl.edu/etd/740.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Kayne A. Computational Fluid Dynamics (CFD) Modeling of Mixed Convection Flows in Building Enclosures. [Thesis]. Washington University in St. Louis; 2012. Available from: https://openscholarship.wustl.edu/etd/740
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
5.
Edeling, Wouter Nico.
Quantification of modelling uncertainties in turbulent flow simulations : Quantification des incertitudes de modélisation dans les écoulements turbulents.
Degree: Docteur es, Mécanique des fluides, 2015, Paris, ENSAM; Technische universiteit (Delft, Pays-Bas)
URL: http://www.theses.fr/2015ENAM0007
► Le but de cette thèse est de faire des simulations prédictives à partir de modèles de turbulence de type RANS (Reynolds-Averaged Navier-Stokes). Ces simulations font…
(more)
▼ Le but de cette thèse est de faire des simulations prédictives à partir de modèles de turbulence de type
RANS (
Reynolds-
Averaged Navier-
Stokes). Ces simulations font l'objet d'un traitement systématique du modèle, de son incertitude et de leur propagation par le biais d'un modèle de calcul prédictif aux incertitudes quantifiées. Pour faire cela, nous utilisons le cadre robuste de la statistique Bayesienne.La première étape vers ce but a été d'obtenir une estimation de l'erreur de simulations
RANS basées sur le modèle de turbulence de Launder-Sharma k-e. Nous avons recherché en particulier à estimer des incertitudes pour les coefficients du modele, pour des écoulements de parois en gradients favorable et défavorable. Dans le but d'estimer la propagation des coefficients qui reproduisent le plus précisemment ces types d'écoulements, nous avons étudié 13 configurations différentes de calibrations Bayesienne. Chaque calibration était associée à un gradient de pression spécifique gràce à un modèle statistique. Nous representont la totalite des incertitudes dans la solution avec une boite-probabilite (p-box). Cette boîte-p représente aussi bien les paramètres de variabilité de l'écoulement que les incertitudes epistemiques de chaque calibration. L'estimation d'un nouvel écoulement de couche-limite est faite pour des valeurs d'incertitudes générées par cette information sur l'incertitude elle-même. L'erreur d'incertitude qui en résulte est consistante avec les mesures expérimentales.Cependant, malgré l'accord avec les mesures, l'erreur obtenue était encore trop large. Ceci est dû au fait que la boite-p est une prédiction non pondérée. Pour améliorer cela, nous avons développé une autre approche qui repose également sur la variabilité des coefficients de fermeture du modèle, au travers de multiples scénarios d'écoulements et de multiples modèles de fermeture. La variabilité est là encore estimée par le recours à la calibration Bayesienne et confrontée aux mesures expérimentales de chaque scénario. Cependant, un scénario-modèle Bayesien moyen (BMSA) est ici utilisé pour faire correspondre les distributions a posteriori à un scénario (prédictif) non mesuré. Contrairement aux boîtes-p, cette approche est une approche pondérée faisant appel aux probabilités des modèles de turbulence, déterminée par les données de calibration. Pour tous les scénarios de prédiction considérés, la déviation standard de l'estimation stochastique est consistante avec les mesures effectuées.Les résultats de l'approche BMSA expriment des barres d'erreur raisonnables. Cependant, afin de l'appliquer à des topologies plus complexes et au-delà de la classe des écoulements de couche-limite, des techniques de modeles de substitution doivent être mises en places. La méthode de la collocation Stochastique-Simplex (SSC) est une de ces techniques et est particulièrement robuste pour la propagation de distributions d'entrée incertaines dans un code de calcul. Néanmois, son utilisation de la triangulation Delaunay peut entrainer un problème de coût prohibitif pour…
Advisors/Committee Members: Cinnella, Paola (thesis director), Bijl, Hester (thesis director).
Subjects/Keywords: Reynolds-Averaged Navier-Stokes; Statistique Bayesienne; Estimation de l'erreur; Reynolds-Averaged Navier-Stokes; Bayesian Statistics; Error estimation
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APA ·
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APA (6th Edition):
Edeling, W. N. (2015). Quantification of modelling uncertainties in turbulent flow simulations : Quantification des incertitudes de modélisation dans les écoulements turbulents. (Doctoral Dissertation). Paris, ENSAM; Technische universiteit (Delft, Pays-Bas). Retrieved from http://www.theses.fr/2015ENAM0007
Chicago Manual of Style (16th Edition):
Edeling, Wouter Nico. “Quantification of modelling uncertainties in turbulent flow simulations : Quantification des incertitudes de modélisation dans les écoulements turbulents.” 2015. Doctoral Dissertation, Paris, ENSAM; Technische universiteit (Delft, Pays-Bas). Accessed January 22, 2021.
http://www.theses.fr/2015ENAM0007.
MLA Handbook (7th Edition):
Edeling, Wouter Nico. “Quantification of modelling uncertainties in turbulent flow simulations : Quantification des incertitudes de modélisation dans les écoulements turbulents.” 2015. Web. 22 Jan 2021.
Vancouver:
Edeling WN. Quantification of modelling uncertainties in turbulent flow simulations : Quantification des incertitudes de modélisation dans les écoulements turbulents. [Internet] [Doctoral dissertation]. Paris, ENSAM; Technische universiteit (Delft, Pays-Bas); 2015. [cited 2021 Jan 22].
Available from: http://www.theses.fr/2015ENAM0007.
Council of Science Editors:
Edeling WN. Quantification of modelling uncertainties in turbulent flow simulations : Quantification des incertitudes de modélisation dans les écoulements turbulents. [Doctoral Dissertation]. Paris, ENSAM; Technische universiteit (Delft, Pays-Bas); 2015. Available from: http://www.theses.fr/2015ENAM0007
University of Technology, Sydney
6.
Niktash, Amirreza.
Investigation into two-sided windcatchers used for room ventilation.
Degree: 2016, University of Technology, Sydney
URL: http://hdl.handle.net/10453/52834
► A windcatcher is a structure for ventilation purposes fitted on the roof of a building to induce the stale inside air to the outdoors and…
(more)
▼ A windcatcher is a structure for ventilation purposes fitted on the roof of a building to induce the stale inside air to the outdoors and supply the fresh outside air into the building.
The experimental studies of windcatcher systems for all cases are obviously costly or even impossible in practice. The assessment of the performance of windcatcher systems using Computational Fluid Dynamics (CFD) is very important for both their designs and improvements; CFD has become a reliable tool for flow analysis in buildings.
This thesis investigates the effects of some key factors on the performance of a two-sided windcatcher fitted on the roof of a typical room. A CFD software package developed by the ESI group is used for the quantitative and qualitative analysis of velocity magnitude, flow patterns, and ventilation flowrate. For all cases, RANS (Reynolds Averaged Navier-Stokes) CFD technique with the standard two-equation K-εturbulence model is employed in steady state conditions for incompressible turbulent air flows. Based on the simulations and analysis, a model is selected. A LES (Large Eddy Simulation) CFD technique employing the Smagorinsky subgrid-scale (SGS) turbulence modelis used for evaluating the selected model in transient conditions. Results from RANS and LES are compared; and they show good agreement.
To verify the computational results, a laboratory scaled model from the selected computational model is constructed and these are compared with the experimental measurements; and fair agreement has been obtained.
All these investigations would lead to a significant development in evaluation and performance of two-sided windcatcher systems. This work has resulted in 8 research publications which are listed in Publications Section.
Subjects/Keywords: Two-sided windcatchers.; Computational Fluid Dynamics (CFD).; RANS (Reynolds Averaged Navier-Stokes) CFD technique.; LES (Large Eddy Simulation) CFD technique.; Smagorinsky subgrid-scale (SGS) turbulence models.
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APA (6th Edition):
Niktash, A. (2016). Investigation into two-sided windcatchers used for room ventilation. (Thesis). University of Technology, Sydney. Retrieved from http://hdl.handle.net/10453/52834
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Niktash, Amirreza. “Investigation into two-sided windcatchers used for room ventilation.” 2016. Thesis, University of Technology, Sydney. Accessed January 22, 2021.
http://hdl.handle.net/10453/52834.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Niktash, Amirreza. “Investigation into two-sided windcatchers used for room ventilation.” 2016. Web. 22 Jan 2021.
Vancouver:
Niktash A. Investigation into two-sided windcatchers used for room ventilation. [Internet] [Thesis]. University of Technology, Sydney; 2016. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/10453/52834.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Niktash A. Investigation into two-sided windcatchers used for room ventilation. [Thesis]. University of Technology, Sydney; 2016. Available from: http://hdl.handle.net/10453/52834
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
7.
Sarkar, Dwaipayan.
A numerical tool for predicting the spatial decay of freestream turbulence.
Degree: 2018, University of Western Ontario
URL: https://ir.lib.uwo.ca/etd/5331
► The present numerical work is an attempt towards modelling of freely decaying homogeneous isotropic turbulence with its application in experimental modelling of the effect of…
(more)
▼ The present numerical work is an attempt towards modelling of freely decaying homogeneous isotropic turbulence with its application in experimental modelling of the effect of incident turbulence on flow around 2D and 3D bluff-bodies. Both steady, Reynolds Averaged Navier Stokes (RANS) and unsteady, Large Eddy Simulation (LES), 3-D numerical computational fluid dynamics (CFD) techniques have been employed to characterise the inviscid decay of large-scale turbulence in terms of the characteristic r.m.s turbulent velocity fluctuations ( ) and the local integral length scale (Lu). The large-scale turbulent properties extracted from the current numerical simulations are inter-related and are shown to behave predominantly as Saffman turbulence, which states Lu3 ≈ constant. The other focus from the current study was on modelling inlet conditions for bluff-bodies in a freestream flow. A set of three-correlation equations are formulated based on the large-scale turbulent properties that are effective in estimating the initial and local freestream turbulence conditions. The set of prediction equations can be deemed useful for researchers developing wind-tunnel models in the presence of freestream turbulence. Additionally, the set of equations is also reliable in determining appropriate near-constant turbulent conditions based on the upstream inlet conditions. The current study aims at designing the region of constant turbulent properties of a desired magnitude that can be helpful for boundary layer and heat transfer studies over a bluff-body.
Subjects/Keywords: Homogeneous; Isotropic; Reynolds Averaged Navier-Stokes (RANS); Large Eddy Simulation (LES); Decay; Computational Fluid Dynamics (CFD); Freestream turbulence; Bluff-body; Other Mechanical Engineering
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APA ·
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MLA ·
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Export
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APA (6th Edition):
Sarkar, D. (2018). A numerical tool for predicting the spatial decay of freestream turbulence. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/5331
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Sarkar, Dwaipayan. “A numerical tool for predicting the spatial decay of freestream turbulence.” 2018. Thesis, University of Western Ontario. Accessed January 22, 2021.
https://ir.lib.uwo.ca/etd/5331.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Sarkar, Dwaipayan. “A numerical tool for predicting the spatial decay of freestream turbulence.” 2018. Web. 22 Jan 2021.
Vancouver:
Sarkar D. A numerical tool for predicting the spatial decay of freestream turbulence. [Internet] [Thesis]. University of Western Ontario; 2018. [cited 2021 Jan 22].
Available from: https://ir.lib.uwo.ca/etd/5331.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Sarkar D. A numerical tool for predicting the spatial decay of freestream turbulence. [Thesis]. University of Western Ontario; 2018. Available from: https://ir.lib.uwo.ca/etd/5331
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Western Ontario
8.
Alfaia de Magalhaes, Ivian Carolina.
The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates.
Degree: 2020, University of Western Ontario
URL: https://ir.lib.uwo.ca/etd/7393
► The present work investigates the effect of free-stream turbulence (FST) on turbulent boundary layers and forced convective heat transfer from flat plates. High resolution, 2-D…
(more)
▼ The present work investigates the effect of free-stream turbulence (FST) on turbulent boundary layers and forced convective heat transfer from flat plates. High resolution, 2-D and 3-D, steady Reynolds-Averaged Navier-Stokes (RANS) simulations using Computational Fluid Dynamics (CFD) techniques were performed to analyze the influence of different free-stream conditions, such as turbulence intensity (TI), integral length scale (Lu) and free-stream velocity (Uo) on local and total skin friction and convective heat transfer coefficients (CHTC), as well as on turbulent boundary layer parameters (boundary layer thickness and momentum thickness). The present study shows that the Shear Stress Transport (SST) k-ω model with the low Reynolds number (Re) approach is the most suitable model for representing incident turbulent flow over isothermal flat plates, since it provides the correct skin friction and Nusselt number for turbulent boundary layers, along with the appropriate streamwise TI decay through the numerical domain. Using the results, a set of non-dimensional correlations for local and total skin friction, momentum thickness, local and total CHTC were developed. These are simple and useful tools for the prediction of skin friction and forced convective heat transfer from flat plates under FST, which can be helpful for many engineering applications such as photovoltaic systems.
Subjects/Keywords: Turbulent boundary layers; Convective heat transfer; Reynolds-Averaged Navier-Stokes (RANS); Computational Fluid Dynamics (CFD); Free-stream turbulence; Flat plates; Other Mechanical Engineering
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APA (6th Edition):
Alfaia de Magalhaes, I. C. (2020). The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/7393
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Alfaia de Magalhaes, Ivian Carolina. “The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates.” 2020. Thesis, University of Western Ontario. Accessed January 22, 2021.
https://ir.lib.uwo.ca/etd/7393.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Alfaia de Magalhaes, Ivian Carolina. “The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates.” 2020. Web. 22 Jan 2021.
Vancouver:
Alfaia de Magalhaes IC. The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates. [Internet] [Thesis]. University of Western Ontario; 2020. [cited 2021 Jan 22].
Available from: https://ir.lib.uwo.ca/etd/7393.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Alfaia de Magalhaes IC. The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates. [Thesis]. University of Western Ontario; 2020. Available from: https://ir.lib.uwo.ca/etd/7393
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Urbana-Champaign
9.
Pomeroy, Brent William.
Wake bursting: a computational and experimental investigation for application to high-lift multielement airfoil design.
Degree: PhD, Aerospace Engineering, 2016, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/90589
► High-lift aerodynamic flowfields are complex, and the potentially-adverse wake development associated with these high-lift systems is not fully understood. Thus, an exhaustive investigation including both…
(more)
▼ High-lift aerodynamic flowfields are complex, and the potentially-adverse wake development associated with these high-lift systems is not fully understood. Thus, an exhaustive investigation including both experimental and computational efforts is needed to gain an increased understanding of the flowfield. Previous work indicates the strong off-the-surface adverse pressure gradients created by flaps may cause the main-element wake to "separate" in an aerodynamic phenomena known as wake bursting. Previous experimental research efforts to study wake bursting over a multielement airfoil are lacking a detailed study of the burst wakes in a wide range of spatial coordinates. In addition, no thorough comparison between the experimentally-captured data and computational simulations of a high-lift multielement airfoil has been performed.
A variety of different experimental and computational tools can be used to study the burst-wake flowfield. These experimental techniques include the standard aerodynamic-performance and flow-visualization techniques in addition to complex wake survey methods. These wake surveys can be executed with one of a variety of probes to capture unsteady or steady data such as pressures or velocities. Because all desired flowfield parameters cannot be captured by one probe, results from different probes must be carefully analyzed and compared to other data such that a full understanding of the flowfield can be gained. Computational methods to study the burst-wake flowfield must adequately solve both the inviscid and viscous regions of the flowfield. Computations can be performed with low-order coupled viscous/inviscid program in addition to more-robust
Navier-
Stokes solvers, such as
Reynolds-
averaged Navier Stokes (
RANS) programs. It is necessary to carefully compare the experimental and computational results such that the flowfield can be understood in greater detail. These comparisons will also yield insight into the effects of experimental testing environments and the weaknesses of computational solvers.
Results for a three-element airfoil, consisting of a main element and a double-slotted flap, were determined using various experimental methods. Experimental results included aerodynamic polars, flow visualization, and wake surveys with both split-film and 7-hole probes. The split-film probe yielded two-dimensional unsteady velocity measurements while the 7-hole probe was use to capture time-
averaged velocity vector, static pressure, and total pressure. The burst-wake region consisted of increased turbulence intensities and extremely-high turbulence production when compared to the flow outside of the wake. An increase in wake thickness with increasing downstream distance was captured from each probe, and the relationship between the wake thickness and freestream conditions was established. Low
Reynolds numbers and increased angle of attack yielded the thickest wakes of all tested freestream conditions. In addition, flaps with extremely small gap sizes also yielded increased…
Advisors/Committee Members: Selig, Michael S (advisor), Selig, Michael S (Committee Chair), Elliott, Gregory S (committee member), Vassberg, John C (committee member), Chamorro, Leonardo P (committee member).
Subjects/Keywords: aerodynamics; high lift; airfoil; airfoil design; wake; separation; bursting; wake bursting; split film; 7-hole; wind tunnel; USM3D; Reynolds-averaged Navier Stokes (RANS); Computational fluid dynamics (CFD)
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APA (6th Edition):
Pomeroy, B. W. (2016). Wake bursting: a computational and experimental investigation for application to high-lift multielement airfoil design. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/90589
Chicago Manual of Style (16th Edition):
Pomeroy, Brent William. “Wake bursting: a computational and experimental investigation for application to high-lift multielement airfoil design.” 2016. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed January 22, 2021.
http://hdl.handle.net/2142/90589.
MLA Handbook (7th Edition):
Pomeroy, Brent William. “Wake bursting: a computational and experimental investigation for application to high-lift multielement airfoil design.” 2016. Web. 22 Jan 2021.
Vancouver:
Pomeroy BW. Wake bursting: a computational and experimental investigation for application to high-lift multielement airfoil design. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2016. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/2142/90589.
Council of Science Editors:
Pomeroy BW. Wake bursting: a computational and experimental investigation for application to high-lift multielement airfoil design. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2016. Available from: http://hdl.handle.net/2142/90589
Virginia Tech
10.
Norman, Adam Edward.
A Fundamental Study of Advance Ratio, Solidity, Turbine Radius, and Blade Profile on the Performance Characteristics of Vertical Axis Turbines (VATs).
Degree: MS, Mechanical Engineering, 2016, Virginia Tech
URL: http://hdl.handle.net/10919/81836
► In this dissertation, various VAT parameters are investigated to determine the effect of the overall efficiency of the turbine at a high Reynolds number. To…
(more)
▼ In this dissertation, various VAT parameters are investigated to determine the effect of the overall efficiency of the turbine at a high
Reynolds number. To increase the efficiency of the vertical axis turbines, 2D CFD simulations are completed in an effort to better understand the physics behind the operation of these turbines. Specifically, the effect of advance ratio, solidity, and wake interactions were investigated. Simulations were completed in OpenFOAM using the k-ω SST turbulence model at a nominal
Reynolds number of 500,000 using a NACA 0015 airfoil. To simulate the motion of the turbine, Arbitrary Mesh Interfacing (AMI) was used. For all of the parameters tested, it was found that the geometric effective angle of attack seen by the turbine blades had a significant impact on the power extracted from the flow. The range of effective angles of attack was found to decrease as the advance ratio increased. In spite of this, a severe loss in the power coefficient occurred at an advance ratio of 2.5 during which the blade experienced dynamic stall. This effect was also seen when the number of turbine blades was changed to four, at a solidity of 1.08. This negative impact on performance was found to be due to the increase in the drag component of the tangential force when dynamic stall occurs. Results indicate that wake interactions between subsequent blades have a large impact on performance especially when the wake interaction alters the flow direction sufficiently to create conditions for dynamic stall.
To improve the performance of the VAT in the presence of dynamic stall, calculations were completed of a static twisted blade profile using GenIDLEST and OpenFOAM. There was found to be no improvement in the lift coefficient when comparing the twisted blade profile with a 2D blade at the same median angle of attack as the twisted blade. To further see the effects of the twisted blade, an effective VAT pitching motion was given to the blade and again compared to a 2D blade with the same motion. In this case there was significant improvement seen in the performance of the twisted blade.
Advisors/Committee Members: Tafti, Danesh K. (committeechair), Battaglia, Francine (committee member), Zuo, Lei (committee member).
Subjects/Keywords: Computational Fluid Dynamics (CFD); Reynolds Averaged Navier-Stokes (RANS); Large Eddy Simulation (LES) vertical axis turbine; dynamics stall; advance ratio; solidity; wake
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APA (6th Edition):
Norman, A. E. (2016). A Fundamental Study of Advance Ratio, Solidity, Turbine Radius, and Blade Profile on the Performance Characteristics of Vertical Axis Turbines (VATs). (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/81836
Chicago Manual of Style (16th Edition):
Norman, Adam Edward. “A Fundamental Study of Advance Ratio, Solidity, Turbine Radius, and Blade Profile on the Performance Characteristics of Vertical Axis Turbines (VATs).” 2016. Masters Thesis, Virginia Tech. Accessed January 22, 2021.
http://hdl.handle.net/10919/81836.
MLA Handbook (7th Edition):
Norman, Adam Edward. “A Fundamental Study of Advance Ratio, Solidity, Turbine Radius, and Blade Profile on the Performance Characteristics of Vertical Axis Turbines (VATs).” 2016. Web. 22 Jan 2021.
Vancouver:
Norman AE. A Fundamental Study of Advance Ratio, Solidity, Turbine Radius, and Blade Profile on the Performance Characteristics of Vertical Axis Turbines (VATs). [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/10919/81836.
Council of Science Editors:
Norman AE. A Fundamental Study of Advance Ratio, Solidity, Turbine Radius, and Blade Profile on the Performance Characteristics of Vertical Axis Turbines (VATs). [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/81836
Univerzitet u Beogradu
11.
Asress, Mulugeta Biadgo. 1983-.
Утицај попречног струјања на аеродинамичка оптерећења
путничког воза ѕа различите конфигурације тла.
Degree: Mašinski fakultet, 2016, Univerzitet u Beogradu
URL: https://fedorabg.bg.ac.rs/fedora/get/o:10465/bdef:Content/get
► Машинство - Ваздухопловство, Железничко машинство / Mechanical engineering - Aerospace engineering, Railway mechanical engineering
Јаки бочни ветрови могу утицати на стабилност воза приликом кретања и…
(more)
▼ Машинство - Ваздухопловство, Железничко машинство /
Mechanical engineering - Aerospace engineering, Railway mechanical
engineering
Јаки бочни ветрови могу утицати на стабилност воза
приликом кретања и у појединим случајевима могу довести до
превртања воза услед појачаних аеродинамичких сила и момената.
Ризик од превртања узрокованог дејством ветра зависи како од
аеродинамичких карактеристика возила тако и од инфраструктуре
железничког коридора по коме воз саобраћа. Са инфраструктурне
стране, места са високим насипима могу да доведу до повећања
аеродинамичких коефицијената док се са стране возила појава
превртања услед јаких бочних ветрова везује за осетљивост облика
воза на дејство бочног ветра. У оквиру ове докторске тезе извршена
је симулација струјања турбулентног бочног ветра око водећег вагона
DF4D путничког воза за различите вредности угла скретања у
случајевима статичког равног терена и насипа висине 6m. Будући да
је аеродинамички аспект проблема блиско повезан са струјањем
ваздуха око воза, ово струјање је разматрано као нестишљиво па је
прорачун вршен коришћењем нестационарних Навије-Стоксових једначина
осредњених Рејнолдсовом статистиком (RANS) у спрези са остваривим
k-ε турбулентним моделом. Свих шест аеродинамичких коефицијената
(бочне силе, силе отпора, силе узгона, момента вањања, момента
пропињања и момента скретања) срачунати су за углове скретања у
интервалу од 0° до 90°. Резултати су показали да свих шест
аеродинамичких коефицијената имају више вредности у случају терена
са насипом у компарацији са кретањем по равном терену. Срачунате
вредности најзначајнијих аеродинамичких коефицијената, као што је
аеродинамички коефицијент момента ваљања, монотоно расту са
повећањем угла скретања до вредности угла скретања од 60° (у
случају равног терена) односно 45° (у случају насипа) пре него што
почну да опадају и/или показују асимптотско понашање. Такође, у
оквиру дисертације разматрана је и зависност структуре струјања од
угла скретања. Природа струјања и његова структура визуелизоване су
графичким приказом струјница и вектора брзине као и контурним
приказом јачине вртложности,статичког притиска и тоталног притиска
по попречном пресеку воза за различите вредности угла скретања. У
оба случаја, резултати указују на повећање величине ротирајућих
вртлога на страни воза у заветрини са повећањем угла скретања што
доводи до стварања области ниског притиска на страни воза у
заветрини односно до појаве високе бочне силе и момента ваљања. За
исти угао скретања, величина ротирајућих вртлога на страни воза у
заветрини је већа у сличају постојања насипа него у случају равног
терена. У оквиру истраживања размотрена је и расподела коефицијента
притиска по обиму попречног пресека воза за углове скретања у
интервалу од 0° до 90° на различитим локацијама по дужини воза.
Коначно, извршен је прорачун критичне брзине ветра за превртање
(Vw-int), односно брзине ветра која доводи до стопроцентног
растерећења точкова на шини у заветрини воза, коришћењем
коефицијента аеродинамичког момента ваљања око шине у заветрини
добијеног…
Advisors/Committee Members: Simonović, Aleksandar. 1975-.
Subjects/Keywords: crosswind; aerodynamics of trains; computational fluid
dynamics; Reynolds-averaged Navier-Stokes equations; k-epsilon
turbulence model; numerical analysis; intrinsic roll-over wind
speed
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APA ·
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APA (6th Edition):
Asress, M. B. 1. (2016). Утицај попречног струјања на аеродинамичка оптерећења
путничког воза ѕа различите конфигурације тла. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:10465/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Asress, Mulugeta Biadgo 1983-. “Утицај попречног струјања на аеродинамичка оптерећења
путничког воза ѕа различите конфигурације тла.” 2016. Thesis, Univerzitet u Beogradu. Accessed January 22, 2021.
https://fedorabg.bg.ac.rs/fedora/get/o:10465/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Asress, Mulugeta Biadgo 1983-. “Утицај попречног струјања на аеродинамичка оптерећења
путничког воза ѕа различите конфигурације тла.” 2016. Web. 22 Jan 2021.
Vancouver:
Asress MB1. Утицај попречног струјања на аеродинамичка оптерећења
путничког воза ѕа различите конфигурације тла. [Internet] [Thesis]. Univerzitet u Beogradu; 2016. [cited 2021 Jan 22].
Available from: https://fedorabg.bg.ac.rs/fedora/get/o:10465/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Asress MB1. Утицај попречног струјања на аеродинамичка оптерећења
путничког воза ѕа различите конфигурације тла. [Thesis]. Univerzitet u Beogradu; 2016. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:10465/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Michigan
12.
Ye, Haixuan.
Development of A Direct-Forcing Immersed-Boundary Method on Unstructured Meshes for Multi-Body Interactions in Air-Water Two-Phase Flows.
Degree: PhD, Naval Architecture & Marine Engineering, 2020, University of Michigan
URL: http://hdl.handle.net/2027.42/162867
► A direct-forcing immersed boundary method (IBM) is developed in the framework of a finite-volume incompressible solver for high-Reynolds-number flows. The method solves governing equations on…
(more)
▼ A direct-forcing immersed boundary method (IBM) is developed in the framework
of a finite-volume incompressible solver for high-
Reynolds-number flows. The method solves governing
equations on a background mesh whose grid lines do not conform to the concerned surface geometry, whereby the difficulty of generating high-quality body-fitted meshes is significantly reduced. The boundary conditions on the surface of the geometry are enforced through interpolation. A unique aspect of the proposed IBM is that the method is compatible with unstructured meshes, and as such can be combined with body-fitted meshes, so that some geometries can be represented by body-fitted meshes, and other geometries are represented by the IBM. The method provides an accurate solution for the cases of moving objects in both single-phase and air-water two-phase flows. The method can also be applied to both steady and unsteady, laminar and turbulent flows. In the current work, the method is implemented for solving the
Reynolds-
Averaged Navier-
Stokes equations, and for turbulent flows, the Spalart-Allmaras turbulence model is used.
A noticeable challenge of using IBMs is the difficulty in resolving boundary layers at high
Reynolds numbers. In this thesis a universal wall function is implemented, which provides a smooth velocity profile from the outer edge of the logarithmic region down to the wall. The wall function improves accuracy when the mesh is not sufficiently fine to resolve the viscous sublayer. As a result, the stringent requirement of near-wall cell spacing for high-
Reynolds-number flows is significantly alleviated.
The Volume-of-Fluid (VoF) method is used for air-water two-phase flows. A field
extension method is used to enforce the boundary condition of the volume fraction on the immersed surface.
Detailed verification and validation studies are performed to demonstrate that the current method is second-order accurate. A careful comparison is presented between the results of the IBM, the experimental data, and other numerical results. The comparison fully demonstrates the accuracy and feasibility of the method by examining the flow field and the force on the immersed surface. The validation case of a ship advancing with a rotating rudder is also performed. The results demonstrate the accuracy, flexibility and efficiency when the IBM is used combined with unstructured body-fitted meshes.
Advisors/Committee Members: Maki, Kevin John (committee member), Fidkowski, Krzysztof J (committee member), Troesch, Armin W (committee member), Young, Yin Lu (committee member).
Subjects/Keywords: Immersed Boundary Method; Finite Volume Method; Reynolds-Averaged Navier-Stokes Equations; Wall Function; Air-water Two-phase Incompressible Flows; OpenFOAM; Naval Architecture and Marine Engineering; Engineering
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APA ·
Chicago ·
MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Ye, H. (2020). Development of A Direct-Forcing Immersed-Boundary Method on Unstructured Meshes for Multi-Body Interactions in Air-Water Two-Phase Flows. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/162867
Chicago Manual of Style (16th Edition):
Ye, Haixuan. “Development of A Direct-Forcing Immersed-Boundary Method on Unstructured Meshes for Multi-Body Interactions in Air-Water Two-Phase Flows.” 2020. Doctoral Dissertation, University of Michigan. Accessed January 22, 2021.
http://hdl.handle.net/2027.42/162867.
MLA Handbook (7th Edition):
Ye, Haixuan. “Development of A Direct-Forcing Immersed-Boundary Method on Unstructured Meshes for Multi-Body Interactions in Air-Water Two-Phase Flows.” 2020. Web. 22 Jan 2021.
Vancouver:
Ye H. Development of A Direct-Forcing Immersed-Boundary Method on Unstructured Meshes for Multi-Body Interactions in Air-Water Two-Phase Flows. [Internet] [Doctoral dissertation]. University of Michigan; 2020. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/2027.42/162867.
Council of Science Editors:
Ye H. Development of A Direct-Forcing Immersed-Boundary Method on Unstructured Meshes for Multi-Body Interactions in Air-Water Two-Phase Flows. [Doctoral Dissertation]. University of Michigan; 2020. Available from: http://hdl.handle.net/2027.42/162867
Delft University of Technology
13.
Kessels, P.C.J. (author).
Finite element discretization of the Spalart-Allmaras turbulence model.
Degree: 2016, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:b5c21532-d84e-49f0-8d18-a181b02e09ac
► The Reynolds-averaged Navier-Stokes equations are numerically solved in a segregated manner, along with the Spalart-Allmaras turbulence model. The Galerkin as well as multiple stabilized finite…
(more)
▼ The Reynolds-averaged Navier-Stokes equations are numerically solved in a segregated manner, along with the Spalart-Allmaras turbulence model. The Galerkin as well as multiple stabilized finite element formulations are derived for the Spalart-Allmaras turbulence model, and tested for robustness. For a turbulent channel flow and a backward facing step case, the Galerkin approach shows to be quite robust by itself, but the multiscale stabilized formulation shows superior robustness in the case of the backward facing step problem, while mostly preserving accuracy.
Aerospace Engineering
Aerodynamics, Wind Energy, Flight Performance and Propulsion
Aerodynamics
Advisors/Committee Members: Hulshoff, S.J. (mentor).
Subjects/Keywords: finite element method; turbulence modeling; Spalart-Allmaras; multiscale; Reynolds-averaged Navier-Stokes
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Manager
APA (6th Edition):
Kessels, P. C. J. (. (2016). Finite element discretization of the Spalart-Allmaras turbulence model. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:b5c21532-d84e-49f0-8d18-a181b02e09ac
Chicago Manual of Style (16th Edition):
Kessels, P C J (author). “Finite element discretization of the Spalart-Allmaras turbulence model.” 2016. Masters Thesis, Delft University of Technology. Accessed January 22, 2021.
http://resolver.tudelft.nl/uuid:b5c21532-d84e-49f0-8d18-a181b02e09ac.
MLA Handbook (7th Edition):
Kessels, P C J (author). “Finite element discretization of the Spalart-Allmaras turbulence model.” 2016. Web. 22 Jan 2021.
Vancouver:
Kessels PCJ(. Finite element discretization of the Spalart-Allmaras turbulence model. [Internet] [Masters thesis]. Delft University of Technology; 2016. [cited 2021 Jan 22].
Available from: http://resolver.tudelft.nl/uuid:b5c21532-d84e-49f0-8d18-a181b02e09ac.
Council of Science Editors:
Kessels PCJ(. Finite element discretization of the Spalart-Allmaras turbulence model. [Masters Thesis]. Delft University of Technology; 2016. Available from: http://resolver.tudelft.nl/uuid:b5c21532-d84e-49f0-8d18-a181b02e09ac
14.
Monier, Jean-François.
Analyse de la modélisation turbulente en écoulements tourbillonnaires : Turbulent modelling analysis on rotating flows.
Degree: Docteur es, Mécanique des fluides, 2018, Lyon
URL: http://www.theses.fr/2018LYSEC015
► L'objectif de la présente étude est d'analyser la modélisation de la turbulence de simulations en moyenne de Reynolds (RANS) dans le cadre d'écoulements de type…
(more)
▼ L'objectif de la présente étude est d'analyser la modélisation de la turbulence de simulations en moyenne de Reynolds (RANS) dans le cadre d'écoulements de type turbomachines, en utilisant des simulations aux grandes échelles (SGE) comme référence. L'étude porte sur deux cas test: un décollement de coin dans une grille d'aubes rectiligne, et un écoulement de jeu pour un aubage isolé dans un jet. Deux lois de comportement, la loi de comportement de Boussinesq et la loi de comportement quadratique (quadratic constitutive relation ou QCR), sont analysées, avec deux versions du modèle de turbulence k-Ω de Wilcox. Les lois de comportement étudiées reposent sur deux hypothèses: une hypothèse d'alignement entre le tenseur de Reynolds et un tenseur construit à partir de l'écoulement moyen, et une hypothèse sur la viscosité turbulente. L'hypothèse d'alignement est étudiée à partir de la SGE, pour laquelle les deux tenseurs sont indépendamment connus, en utilisant un indicateur construit sur le produit scalaire des tenseurs. Les résultats sont présentés sous forme d'une fonction de répartition de la valeur de l'indicateur pour le domaine complet, puis pour trois sous-domaines d'intérêt: l'entrée, une région où l'écoulement interagit fortement avec les parois, et une région où l'écoulement est fortement tourbillonnaire. L'hypothèse d'alignement n'est que rarement valide pour la loi de comportement de Boussinesq. Pour la QCR, les résultats sont meilleurs en entrée, comparé à la loi de Boussinesq. Il ne sont cependant pas meilleurs pour les régions où l'écoulement est plus tourbillonnaire. Une amélioration de la loi de comportement est nécessaire pour pouvoir faire progresser la modélisation turbulente en RANS. En revanche, l'utilisation de l'énergie cinétique turbulente et du taux de dissipation spécifique semble correcte pour estimer la valeur de la viscosité turbulente. L'analyse de la modélisation de l'équation d'énergie cinétique turbulente (ECT) est réalisée au travers d'une comparaison terme à terme avec l'équation d'ECT résolue par la SGE. Les résultats SGE présentent une turbulence qui n'est pas à l'équilibre : la production et la dissipation ne sont pas superposées, et le terme de transport est important. Pour le RANS, la turbulence est à l'équilibre : la production et la dissipation sont superposées, et le terme de transport est de faible intensité. Un modèle de turbulence qui prend en compte le déséquilibre est nécessaire pour améliorer ce point. En dernier lieu, une nouvelle formulation hybride RANS/SGE est proposée, fondée sur la distance à la paroi en unités de paroi. La formulation est validée dans un canal bi-périodique et un premier essai est réalisé sur le cas de décollement de coin, mais d'autres analyses sont nécessaires avant que cette formulation ne soit fonctionnelle.
The present study aims at analysing turbulence modelling in Reynolds-averaged Navier- Stokes (RANS) simulations, in the context of turbomachinery flows, using large-eddy simulations (LES) as references. Two test cases are considered: a…
Advisors/Committee Members: Shao, Liang (thesis director).
Subjects/Keywords: Simulation aux grandes échelles (SGE); Simulation en moyenne de Reynolds (RANS); Modélisation de la turbulence; Loi de comportement; Bilan d'énergie cinétique turbulente; Décollement de coin; Écoulement de jeu; Hybride RANS/SGE; Large-eddy simulation; Reynolds-averaged Navier-Stokes;
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APA (6th Edition):
Monier, J. (2018). Analyse de la modélisation turbulente en écoulements tourbillonnaires : Turbulent modelling analysis on rotating flows. (Doctoral Dissertation). Lyon. Retrieved from http://www.theses.fr/2018LYSEC015
Chicago Manual of Style (16th Edition):
Monier, Jean-François. “Analyse de la modélisation turbulente en écoulements tourbillonnaires : Turbulent modelling analysis on rotating flows.” 2018. Doctoral Dissertation, Lyon. Accessed January 22, 2021.
http://www.theses.fr/2018LYSEC015.
MLA Handbook (7th Edition):
Monier, Jean-François. “Analyse de la modélisation turbulente en écoulements tourbillonnaires : Turbulent modelling analysis on rotating flows.” 2018. Web. 22 Jan 2021.
Vancouver:
Monier J. Analyse de la modélisation turbulente en écoulements tourbillonnaires : Turbulent modelling analysis on rotating flows. [Internet] [Doctoral dissertation]. Lyon; 2018. [cited 2021 Jan 22].
Available from: http://www.theses.fr/2018LYSEC015.
Council of Science Editors:
Monier J. Analyse de la modélisation turbulente en écoulements tourbillonnaires : Turbulent modelling analysis on rotating flows. [Doctoral Dissertation]. Lyon; 2018. Available from: http://www.theses.fr/2018LYSEC015
Indian Institute of Science
15.
Srinivasa Murthy, P.
Low Reynolds Number Airfoil Aerodynamics.
Degree: PhD, Faculty of Engineering, 2006, Indian Institute of Science
URL: http://etd.iisc.ac.in/handle/2005/229
► In this thesis we describe the development of Reynolds- averaged Navier Stokes code for the flow past two- dimensional configuration. Particularly, emphasis has been laid…
(more)
▼ In this thesis we describe the development of
Reynolds-
averaged Navier Stokes code for the flow past two- dimensional configuration. Particularly, emphasis has been laid on the study of low
Reynolds number airfoil aerodynamics.
The thesis consists of five chapters covering the back ground history, problem formulation, method of solution and discussion of the results and conclusion.
Chapter I deals with a detailed background history of low
Reynolds number aerodynamics, problem associated with it, state of the art, its importance in practical applications in aircraft industries.
Chapter II describes the mathematical model of the flow physics and various levels of approximations. Also it gives an account of complexity of the
equations at low
Reynolds number regarding flow separation, transition and reattachment.
Chapter III describes method of solution, numerical algorithm developed, description of various upwind schemes, grid system, finite volume discrieti-zation of the governing
equations described in Chapter II.
Chapter IV describes the application of the newly developed
Navier Stokes code for the test cases from GAMM Workshop proceedings. Also it describes validation of the code for Euler solutions, Blasius solution for the flow past flat plate and compressible
Navier Stokes solution for the flow past NACA 0012 Airfoil at low
Reynolds number.
Chapter V describes the application of the
Navier Stokes code for the more test cases of current practical interest . In this chapter laminar separation bubble characteristics are investigated in detail regarding formation, growth and shedding in an unsteady environment.
Finally the conclusion is drawn regarding the robustness of the newly developed code in predicting the airfoil aerodynamic characteristics at low
Reynolds number both in steady and unsteady environment.
Lastly, suggestion for future work has been highlighted.
Advisors/Committee Members: Holla, V S (advisor), Kamath, Hemanth (advisor).
Subjects/Keywords: Aeronautics; Airfoils - Aerodynamics; Reynolds number; Navier Stokes Code; Flow Physics; Viscous Flow; Grid Generation; Reynolds Averaged Navier Stokes (RANS) Solution; Euler Solution; Baldwin-Lomax Turbulence Model
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APA (6th Edition):
Srinivasa Murthy, P. (2006). Low Reynolds Number Airfoil Aerodynamics. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/229
Chicago Manual of Style (16th Edition):
Srinivasa Murthy, P. “Low Reynolds Number Airfoil Aerodynamics.” 2006. Doctoral Dissertation, Indian Institute of Science. Accessed January 22, 2021.
http://etd.iisc.ac.in/handle/2005/229.
MLA Handbook (7th Edition):
Srinivasa Murthy, P. “Low Reynolds Number Airfoil Aerodynamics.” 2006. Web. 22 Jan 2021.
Vancouver:
Srinivasa Murthy P. Low Reynolds Number Airfoil Aerodynamics. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2006. [cited 2021 Jan 22].
Available from: http://etd.iisc.ac.in/handle/2005/229.
Council of Science Editors:
Srinivasa Murthy P. Low Reynolds Number Airfoil Aerodynamics. [Doctoral Dissertation]. Indian Institute of Science; 2006. Available from: http://etd.iisc.ac.in/handle/2005/229
16.
Kurokawa, Fernando Akira.
Um esquema \"upwind\" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres.
Degree: PhD, Ciências de Computação e Matemática Computacional, 2009, University of São Paulo
URL: http://www.teses.usp.br/teses/disponiveis/55/55134/tde-20052009-140841/
;
► Apesar de as EDPS que modelam leis de conservação e problemas em dinâmica dos fluídos serem bem estabelecidas, suas soluções numéricas continuam ainda desafiadoras. Em…
(more)
▼ Apesar de as EDPS que modelam leis de conservação e problemas em dinâmica dos fluídos serem bem estabelecidas, suas soluções numéricas continuam ainda desafiadoras. Em particular, há dois desafios associados à computação e ao entendimento desses problemas: um deles é a formação de descontinuidades (choques) e o outro é o fenômeno turbulência. Ambos os desafios podem ser atribuídos ao tratamento dos termos advectivos não lineares nessas equações de transporte. Dentro deste canário, esta tese apresenta o estudo do desenvolvimento de um novo esquema üpwindd̈e alta resolução e sua associação com modelagem da turbulência. O desempenho do esquema é investigado nas soluções da equação de advecção 1D com dados iniciais descontínuos e de problemas de Riemann 1D para as equações de Burgers, Euler e águas rasas. Além disso, são apresentados resultados numéricos de escoamentos incompressíveis 2D e 3D no regime laminar a altos números de Reynolds. O novo esquema é então associado à modelagem \'capa-́ \'epsilond́a turbulência para a simulação numérica de escoamentos incompressíveis turbulentos 2D e 3D com superfícies livres móveis. Aplicação, verificação e validação dos métodos numéricos são também fornecidas
Althought the PDEs that model conservation laws and fluid dynamics problems are well established, their numerical solutions have presented a continuing challenge. In particular, there are two challenges associated with the computation and the understanding of these problems, namely, formation of shocks and turbulence. Both challenges can be attributed to the nonlinear advection terms of these transport equations. In this scenario, this thesis presents the study of the development of a new high-resolution upwind scheme and its association with turbulence modelling. The performance of the scheme is investigated by solving the 1D advection equation with discontinuous initial data 1D Riemann problems for Burgers, Euler and shallow water equations. Besides, numerical results for 2D and 3D incompressible laminar flows at high Reynolds number are presented. The new scheme is then associated with the \'capa - épsilont́urbulence model for the simulation of 2D and 3D incompressible turbulent flows with moving free surfaces. Application, verification and validation of the numerical methods are also provided
Advisors/Committee Members: Ferreira, Valdemir Garcia, Tomé, Murilo Francisco.
Subjects/Keywords: Averaged Navier-Stokes equations; Conservation laws; Equações de Navier-Stokes; Equações médias de Reynolds; Escoamentos com superfícies livres; Esquema "upwind" de alta resolução; Finite difference method; Free surface flows; High-resolution upwind scheme; Método de diferenças finitas; Modelagem 'capa'- ' epsilon' da turbulência; Navier-Stokes equations; Numerical simulation; Solução numérica de leis de conservação; Turbullence modeling
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APA ·
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APA (6th Edition):
Kurokawa, F. A. (2009). Um esquema \"upwind\" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres. (Doctoral Dissertation). University of São Paulo. Retrieved from http://www.teses.usp.br/teses/disponiveis/55/55134/tde-20052009-140841/ ;
Chicago Manual of Style (16th Edition):
Kurokawa, Fernando Akira. “Um esquema \"upwind\" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres.” 2009. Doctoral Dissertation, University of São Paulo. Accessed January 22, 2021.
http://www.teses.usp.br/teses/disponiveis/55/55134/tde-20052009-140841/ ;.
MLA Handbook (7th Edition):
Kurokawa, Fernando Akira. “Um esquema \"upwind\" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres.” 2009. Web. 22 Jan 2021.
Vancouver:
Kurokawa FA. Um esquema \"upwind\" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres. [Internet] [Doctoral dissertation]. University of São Paulo; 2009. [cited 2021 Jan 22].
Available from: http://www.teses.usp.br/teses/disponiveis/55/55134/tde-20052009-140841/ ;.
Council of Science Editors:
Kurokawa FA. Um esquema \"upwind\" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres. [Doctoral Dissertation]. University of São Paulo; 2009. Available from: http://www.teses.usp.br/teses/disponiveis/55/55134/tde-20052009-140841/ ;
University of Maryland
17.
Voegele, Andrew.
Numerical Characterization and Modeling of Adiabatic Slot Film Cooling.
Degree: Aerospace Engineering, 2011, University of Maryland
URL: http://hdl.handle.net/1903/11913
► Film cooling is a technique used to protect critical surfaces in combustors, thrust chambers, turbines and nozzles from hot, chemically reacting gases. Accurately predicting the…
(more)
▼ Film cooling is a technique used to protect critical surfaces in combustors, thrust chambers, turbines and nozzles from hot, chemically reacting gases. Accurately predicting the film's performance is especially challenging in the vicinity of the wall and the film injection plane due to the complex interactions of two highly turbulent, shearing, boundary layer flows. Properly characterizing the streams at the inlet of a numerical simulation and the choice of turbulence model are crucial to accurately predicting the decay of the film. To address these issues, this study employs a
RANS solver that is used to model a film cooled wall. Menter's baseline model, and shear-stress transport model and the Spalart-Allmaras model are employed to determine the effect on film cooling predictions. Several methods for prescribing the inlet planes are explored. These numerical studies are compared with experimental data obtained in a UMD film cooling wind tunnel.
Advisors/Committee Members: Marshall, André W (advisor).
Subjects/Keywords: Aerospace engineering; Film Cooling; Large Eddy Simulation; LES; RANS; Reynolds Average Navier Stokes; Slot
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APA (6th Edition):
Voegele, A. (2011). Numerical Characterization and Modeling of Adiabatic Slot Film Cooling. (Thesis). University of Maryland. Retrieved from http://hdl.handle.net/1903/11913
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Voegele, Andrew. “Numerical Characterization and Modeling of Adiabatic Slot Film Cooling.” 2011. Thesis, University of Maryland. Accessed January 22, 2021.
http://hdl.handle.net/1903/11913.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Voegele, Andrew. “Numerical Characterization and Modeling of Adiabatic Slot Film Cooling.” 2011. Web. 22 Jan 2021.
Vancouver:
Voegele A. Numerical Characterization and Modeling of Adiabatic Slot Film Cooling. [Internet] [Thesis]. University of Maryland; 2011. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/1903/11913.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Voegele A. Numerical Characterization and Modeling of Adiabatic Slot Film Cooling. [Thesis]. University of Maryland; 2011. Available from: http://hdl.handle.net/1903/11913
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
North Carolina State University
18.
Ranganath, Bhargav Bindiganavile.
A Model-Based Closure Approach for Turbulent Combustion using the One-Dimensional Turbulence Model.
Degree: PhD, Mechanical Engineering, 2007, North Carolina State University
URL: http://www.lib.ncsu.edu/resolver/1840.16/5637
► A new model-based closure approach for turbulent combustion using the One-Dimensional turbulence model (ODT) is developed and validated in context to a turbulent jet diffusion…
(more)
▼ A new model-based closure approach for turbulent combustion using the One-Dimensional turbulence model (ODT) is developed and validated in context to a turbulent jet diffusion flame. The interaction of turbulence and chemistry provides interesting finite rate chemistry effects including the phenomena of extinction and re-ignition. The ODT model resolves both spatially and temporally all the scales in a turbulent reaction flow problem, thus, combining the accuracy of a DNS like solver with efficiency by reduction in the number of dimensions. The closure approach is based on identifying the mechanisms responsible for the above mentioned effects and parameterizing the ODT results with a minimum set of scalars transported in the coarse grained solvers like the
Reynolds-
Averaged Navier-
Stokes (
RANS) or Large Eddy Simulation (LES). Thus, the closure from ODT is based on a "one-way" coupling between the coarse grained solvers and ODT.
Two approaches for closure are developed in the present work with respect to a
RANS solver; however, they can be easily extended to LES. The first approach relies on ODT to provide the history effects associated with the geometry, which represent the interactions of turbulence and chemistry, by tabulating scalar statistics (first and second moments) on two parameters measuring, the extent of mixing, the radial mean mixture fraction, and the extent of entrainment, the centerline mean mixture fraction. However, based on the above parameterization, the approach is limited to jet diffusion flame geometry. Furthermore, the closure requires a one to one correspondence between the flames simulated in the coarse grained solver and ODT. As a second approach, the results from ODT are parameterized based on general representative scalars; mixture fraction, which specifies the mixedness of the mixture and temperature, which specifies the reactedness of the mixture. The history effects associated with the flow geometry are provided by the
RANS solver in the form of probability distribution functions (PDFs).
Two classes of turbulent jet diffusion flames; hydrogen⁄air (Flame H3) and piloted methane/air (Sandia flames D and F), are considered for validation of the above ODT-based closure approaches. The piloted methane air flames, owing to higher turbulence, exhibit severe extinction in the near field followed by re-ignition around the flame height. Good comparisons of the conditional statistics for temperature and reactive scalars with the experiments are obtained for both the flames. Good predictions of entrainment as well as mixing for both the flames, as seen in the comparisons of Favre
averaged axial and radial profiles, are obtained. Furthermore, the correct trends of extinction and re-ignition are predicted successfully for the piloted methane/air flames. Thus, the results show the capability of ODT to address the closure needs for a turbulent combustion problem both at molecular length scales (conditional profiles) and integral length scales (Favre
averaged axial and radial profile)…
Advisors/Committee Members: Dr. Tarek Echekki, Committee Chair (advisor), Dr. William Roberts, Committee Member (advisor), Dr. Kevin Lyons, Committee Member (advisor), Dr. Zhilin Li, Committee Member (advisor).
Subjects/Keywords: Reynolds-Averaged Navier-Stokes (RANS); Non-premixed Flames; Turbulent Combustion; One-Dimensional Turbulence Model
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APA ·
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APA (6th Edition):
Ranganath, B. B. (2007). A Model-Based Closure Approach for Turbulent Combustion using the One-Dimensional Turbulence Model. (Doctoral Dissertation). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/5637
Chicago Manual of Style (16th Edition):
Ranganath, Bhargav Bindiganavile. “A Model-Based Closure Approach for Turbulent Combustion using the One-Dimensional Turbulence Model.” 2007. Doctoral Dissertation, North Carolina State University. Accessed January 22, 2021.
http://www.lib.ncsu.edu/resolver/1840.16/5637.
MLA Handbook (7th Edition):
Ranganath, Bhargav Bindiganavile. “A Model-Based Closure Approach for Turbulent Combustion using the One-Dimensional Turbulence Model.” 2007. Web. 22 Jan 2021.
Vancouver:
Ranganath BB. A Model-Based Closure Approach for Turbulent Combustion using the One-Dimensional Turbulence Model. [Internet] [Doctoral dissertation]. North Carolina State University; 2007. [cited 2021 Jan 22].
Available from: http://www.lib.ncsu.edu/resolver/1840.16/5637.
Council of Science Editors:
Ranganath BB. A Model-Based Closure Approach for Turbulent Combustion using the One-Dimensional Turbulence Model. [Doctoral Dissertation]. North Carolina State University; 2007. Available from: http://www.lib.ncsu.edu/resolver/1840.16/5637
Indian Institute of Science
19.
Deevi, Sri Vallabha.
Large Eddy Simulation of Multiphase Flows.
Degree: PhD, Faculty of Engineering, 2018, Indian Institute of Science
URL: http://etd.iisc.ac.in/handle/2005/3656
► Multiphase flows are a common phenomenon. Rains, sediment transport in rivers, snow and dust storms, mud slides and avalanches are examples of multiphase flows occurring…
(more)
▼ Multiphase flows are a common phenomenon. Rains, sediment transport in rivers, snow and dust storms, mud slides and avalanches are examples of multiphase flows occurring in nature. Blood flow is an example of multiphase flow in the human body, which is of vital importance for survival. Multiphase flows occur widely in industrial applications from hydrocarbon extrac-tion to fuel combustion in engines, from spray painting to spray drying, evaporators, pumps and pneumatic conveying. Predicting multiphase flows is of vital importance to understand natural phenomenon and to design and improve industrial processes. Separated flows and dispersed flows are two types of multiphase flows, which occur together in many industrial applications. Physical features of these two classes are different and the transition from one to another involves complex flow physics.
Experimental studies of multiphase flows are not easy, as most real world phenomenon cannot be scaled down to laboratory models. Even for those phenomenon that can be demonstrated at lab-oratory scale, rescaling to real world applications requires mathematical models. There are many challenges in experimental measurements of multiphase flows as well. Measurement techniques well suited for single phase flows have constraints when measuring multiphase phenomenon. Un-certainty in experimental measurements poses considerable difficulties in validating numerical models developed for predicting these flows. Owing to the computational effort required, direct simulation of multiphase flows, even for small scale real world applications is out of present scope. Numerical methods have been developed for dealing with each class of flow separately, that in-volves use of models for phenomenon that is computationally demanding.
Reynolds Averaged Navier-
Stokes (
RANS) methods for predicting multiphase flows place strong requirements on turbulence models, as information about fluctuating quantities in the field, that have significant effects on dispersed phase, is not available. Large Eddy Simulation (LES) gives better predictions than
RANS as the instantaneous field data is available and large scale unsteadiness that effects the dispersed phase can be captured. Recent LES studies of multiphase flows showed that the sub-grid-scale (SGS) model used for the continuous phase has an effect on the evolution of the dispersed phase.
In this work, LES of multiphase flows is performed using Explicit Filtering Large Eddy Sim-ulation method. In this method, spatial derivatives are computed using higher order compact schemes that have spectral-like resolution. SGS modeling is provided by the use of a filter with smoothly falling transfer function. This method is mathematically consistent and converges to a DNS as the grid is refined. It has been successfully applied to combustion and aero-acoustics and this work is the first application of the method to multiphase flows. Study of dispersed multiphase flows was carried out in this work. Modeling of the dispersed phase is kept simple since the in-tention was to evaluate the…
Advisors/Committee Members: Mathew, Joseph (advisor).
Subjects/Keywords: Aerodyamic noise-aircraft engine; Particle-ladden Flows; Modeling Multiphase Flows; Explicit filtering large eddy simulation; Turbulent Round Jet - Simulations; Particle-laden Jets; Large Eddy Simulation (LES); Reynolds Averaged Navier-Stokes (RANS) Methods; Large Eddy Simulation Method; Aerospace Engineering
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APA ·
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MLA ·
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Manager
APA (6th Edition):
Deevi, S. V. (2018). Large Eddy Simulation of Multiphase Flows. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/3656
Chicago Manual of Style (16th Edition):
Deevi, Sri Vallabha. “Large Eddy Simulation of Multiphase Flows.” 2018. Doctoral Dissertation, Indian Institute of Science. Accessed January 22, 2021.
http://etd.iisc.ac.in/handle/2005/3656.
MLA Handbook (7th Edition):
Deevi, Sri Vallabha. “Large Eddy Simulation of Multiphase Flows.” 2018. Web. 22 Jan 2021.
Vancouver:
Deevi SV. Large Eddy Simulation of Multiphase Flows. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2018. [cited 2021 Jan 22].
Available from: http://etd.iisc.ac.in/handle/2005/3656.
Council of Science Editors:
Deevi SV. Large Eddy Simulation of Multiphase Flows. [Doctoral Dissertation]. Indian Institute of Science; 2018. Available from: http://etd.iisc.ac.in/handle/2005/3656
Indian Institute of Science
20.
Javed, Afroz.
Compressible Mixing of Dissimilar Gases.
Degree: PhD, Faculty of Engineering, 2018, Indian Institute of Science
URL: http://etd.iisc.ac.in/handle/2005/3295
► This thesis is concerned with the study of parallel mixing of two dissimilar gases under compressible conditions in the confined environment. A number of numerical…
(more)
▼ This thesis is concerned with the study of parallel mixing of two dissimilar gases under compressible conditions in the confined environment. A number of numerical studies are reported in the literature for the compressible mixing of two streams of gases where (1) both the streams are of similar gases at the same temperatures, (2) both the streams are at different temperatures with similar gases, and (3) dissimilar gases are with nearly equal temperatures. The combination of dissimilar gases at large temperature difference, mixing under compressible conditions, as in the case of scramjet propulsion, has not been adequately addressed numerically. Also many of the earlier studies have used two dimensional numerical simulation and showed good match with the experimental results on mixing layers that are inherently three dimensional in nature. In the present study, both two-dimensional (2-d) and three dimensional (3-d) studies are reported and in particular the effect of side wall on the three dimensionality of the flow field is analyzed, and the reasons of the good match of two dimensional simulations with experimental results have been discussed.
Both two dimensional and three dimensional model free simulations have been conducted for a flow configuration on which experimental results are available. In this flow configuration, the mixing duct has a rectangular cross section with height to width ratio of 0.5. In the upper part of the duct hydrogen gas at a temperature of 103 K is injected through a single manifold of two Ludweig tubes and in the lower part of the duct nitrogen gas at a temperature of 2436 K is supplied through an expansion tube, both the gases are at Mach numbers of 3.1 and 4.0 respectively. Measurements in the experiment are limited to wall pressures and heat flux. The choice of this experimental condition gives an opportunity to study the effect of large temperature difference on the mixing of two dissimilar gases with large molecular weights under compressible conditions.
Both two dimensional and three dimensional model free simulations are carried out using higher order numerical scheme (4th order spatial and 2nd order temporal) to understand the structure and evolution of supersonic confined mixing layer of similar and dissimilar gases. Two dimensional simulations are carried out by both SPARK (finite difference method) and OpenFOAM (finite volume method based open source software that was specially picked out and put together), while 3D model free simulations are carried out by OpenFOAM. A fine grid structure with higher grid resolution near the walls and shear layer is chosen. The effect of forcing of fluctuations on the inlet velocity shows no appreciable change in the fully developed turbulent region of the flow. The flow variables are
averaged after the attainment of statistical steady state established through monitoring the concentration of inert species introduced in the initial guess. The effect of side wall on the flow structure on the mixing layer is studied by comparing the simulation…
Advisors/Committee Members: Paul, P J (advisor), Chakraborty, Debasis (advisor).
Subjects/Keywords: Gases - Compressibility; Gases - Mixing; Dissimilar Gases - Mixing; Gas Flow; Gas Dynamics; Dissimilar Gases - Numerical Simulaltions; Turbulent Prandtl Number; Turbulent Schmidt Number; SPARK 2D Methodology; OpenFOAM Methodology; RANS Methodology; Reynolds Averaged Navier Stokes Equation; Compressible Mixing Layer; Aerospace Engineering
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APA (6th Edition):
Javed, A. (2018). Compressible Mixing of Dissimilar Gases. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/3295
Chicago Manual of Style (16th Edition):
Javed, Afroz. “Compressible Mixing of Dissimilar Gases.” 2018. Doctoral Dissertation, Indian Institute of Science. Accessed January 22, 2021.
http://etd.iisc.ac.in/handle/2005/3295.
MLA Handbook (7th Edition):
Javed, Afroz. “Compressible Mixing of Dissimilar Gases.” 2018. Web. 22 Jan 2021.
Vancouver:
Javed A. Compressible Mixing of Dissimilar Gases. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2018. [cited 2021 Jan 22].
Available from: http://etd.iisc.ac.in/handle/2005/3295.
Council of Science Editors:
Javed A. Compressible Mixing of Dissimilar Gases. [Doctoral Dissertation]. Indian Institute of Science; 2018. Available from: http://etd.iisc.ac.in/handle/2005/3295
Indian Institute of Science
21.
Allamaprabhu, Yaravintelimath.
Turbulence Modeling for Predicting Flow Separation in Rocket Nozzles.
Degree: PhD, Faculty of Engineering, 2018, Indian Institute of Science
URL: http://etd.iisc.ac.in/handle/2005/3046
► Convergent-Divergent (C-D) nozzles are used in rocket engines to produce thrust as a reaction to the acceleration of hot combustion chamber gases in the opposite…
(more)
▼ Convergent-Divergent (C-D) nozzles are used in rocket engines to produce thrust as a reaction to the acceleration of hot combustion chamber gases in the opposite direction. To maximize the engine performance at high altitudes, large area ratio, bell-shaped or contoured nozzles are used. At lower altitudes, the exit pressure of these nozzles is lower than the ambient pressure. During this over-expanded condition, the nozzle-internal flow adapts to the ambient pressure through an oblique shock. But the boundary layer inside the divergent portion of the nozzle is unable to withstand the pressure rise associated with the shock, and consequently flow separation is induced.
Numerical simulation of separated flows in rocket nozzles is challenging because the existing turbulence models are unable to correctly predict shock-induced flow separation. The present thesis addresses this problem. Axisymmetric, steady-state,
Reynolds-
Averaged Navier-
Stokes (
RANS) simulations of a conical nozzle and three sub-scale contoured nozzles were carried out to numerically predict flow separation in over-expanded rocket nozzles at different nozzle pressure ratios (NPR). The conical nozzle is the JPL 45◦-15◦ and the contoured nozzles are the VAC-S1, the DLR-PAR and the VAC-S6-short. The commercial CFD code ANSYS FLUENT 13 was first validated for simulation of separated cold gas flows in the VAC-S1 nozzle. Some modeling issues in the numerical simulations of flow separation in rocket nozzles were determined. It is recognized that compressibility correction, nozzle-lip thickness and upstream-extension of the external domain are the sources of uncertainty, besides turbulence modeling.
In high-speed turbulent flows, compressibility is known to affect dissipation rate of turbulence kinetic energy. As a consequence, a reduction in the spreading rate of supersonic mixing layers occurs. Whereas, the standard turbulence models are developed and calibrated for incompressible flows and hence, do not account for this effect. ANSYS FLUENT uses the compressibility correction proposed by Wilcox [1] which modifies the turbulence dissipation terms based on turbulent Mach number. This, as shown in this thesis, may not be appropriate to the prediction of flow separation in rocket nozzles. Simulation results of the standard SST model, with and without the compressibility correction, are compared with the experimental data at NPR=22 for the DLR-PAR nozzle. Compressibility correction is found to cause under-prediction of separation location and hence its use in the prediction of flow separation is not recommended.
In the literature, computational domains for the simulation of DLR subscale nozzles have thick nozzle-lips whereas for the VAC subscale nozzles they have no nozzle-lip. Effect of nozzle-lip thickness on flow separation is studied in the DLR-PAR nozzle by varying its nozzle-lip thickness. It is found that nozzle-lip thickness significantly influences both separation location and post-separation pressure recovery by means of the recirculation bubbles…
Advisors/Committee Members: Lakshmisha, K N (advisor), Raghunandan, B N (advisor).
Subjects/Keywords: Rocket Nozzles; Nozzle Flow Seperation; Turbulence Modeling; Contoured Rocket Nozzles; Rocket Nozzle Flow Seperation - Numerical Simulation; Reynolds Averaged Navier-stokes (RANS) Simulations; Spalart-Allmaras (SA) Turbulence Model; Shear Stress Transport (SST) Turbulence Model; Rocket Nozzle Contours; Shear Stress Transport; SST Model; Aerospace Engineering
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APA (6th Edition):
Allamaprabhu, Y. (2018). Turbulence Modeling for Predicting Flow Separation in Rocket Nozzles. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/3046
Chicago Manual of Style (16th Edition):
Allamaprabhu, Yaravintelimath. “Turbulence Modeling for Predicting Flow Separation in Rocket Nozzles.” 2018. Doctoral Dissertation, Indian Institute of Science. Accessed January 22, 2021.
http://etd.iisc.ac.in/handle/2005/3046.
MLA Handbook (7th Edition):
Allamaprabhu, Yaravintelimath. “Turbulence Modeling for Predicting Flow Separation in Rocket Nozzles.” 2018. Web. 22 Jan 2021.
Vancouver:
Allamaprabhu Y. Turbulence Modeling for Predicting Flow Separation in Rocket Nozzles. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2018. [cited 2021 Jan 22].
Available from: http://etd.iisc.ac.in/handle/2005/3046.
Council of Science Editors:
Allamaprabhu Y. Turbulence Modeling for Predicting Flow Separation in Rocket Nozzles. [Doctoral Dissertation]. Indian Institute of Science; 2018. Available from: http://etd.iisc.ac.in/handle/2005/3046
University of Cambridge
22.
Sitte, Michael Philip.
Modelling of spray combustion with doubly conditional moment closure.
Degree: PhD, 2019, University of Cambridge
URL: https://doi.org/10.17863/CAM.39071
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.774699
► Turbulent spray combustion is characterised by a strong coupling of evaporation, mixing and chemical reaction. This leads to a wide spectrum of combustion regimes, where…
(more)
▼ Turbulent spray combustion is characterised by a strong coupling of evaporation, mixing and chemical reaction. This leads to a wide spectrum of combustion regimes, where self-propagating premixed flames and diffusion-controlled non-premixed flames may occur simultaneously within the same flame. The physical processes involved in spray combustion and their interaction take place over a broad range of scales, which makes their modelling in numerical simulations challenging. This thesis presents the development of Doubly Conditional Moment Closure (DCMC) for the modelling of turbulent spray combustion. This modelling approach allows us to consider the effects of finite-rate chemistry and spray evaporation on the flame. Using a parametrisation of the flame structure, based on mixture fraction and reaction progress variable permits us to resolve premixed, non-premixed and intermediate combustion modes. In the first part of this thesis, the model development is presented. With its foundation as a statistical model, DCMC does not require any strong assumption in terms of the combustion mode or regime. The DCMC equation is derived in a general form, which involves only a minimum number of modelling assumptions about the physical processes involved. Closure for the DCMC equation is discussed and a complete set of models is suggested. Since little experience exists in the modelling of doubly-conditional terms, the closure models were generalised from conventional Conditional Moment Closure (CMC) or adapted from other combustion models with similar parametrisation. In the second part, the DCMC model is validated for two test flames. The DCMC model was first applied to the Cambridge spray jet flame using the Reynolds-Averaged Navier-Stokes (RANS) approach. This flame is characterised by significant pre-vaporisation and behaves as a propagating spray flame, with similarities to premixed flames, but with small-scale inhomogeneity in the gaseous mixture and the presence of liquid droplet interacting with the flame - a problem which requires the doubly-conditional description of the flame structure employed in the DCMC model. The role of the spray terms on the flame structure and mixing field were assessed using RANS and promising results were obtained. Finally, a Large-Eddy Simulation (LES) with DCMC acting as sub-grid scale combustion model was applied to the Rouen spray jet flame. LES-DCMC was found to accurately predict the spray statistics, lift-off height and flame shape. Small-scale effects of the spray on the flame could be resolved thanks to the doubly-conditional parametrisation of the flame structure. Temporal fluctuations and spatial variations of the flame structure were investigated. Spatial gradients of the doubly-conditional flame structure were small and convective transport was found to play a minor role on the flame structure compared to the effects of micro-mixing and chemical reaction in the DCMC equation. The findings of this work suggest that, besides spray combustion, DCMC shows great potential for the…
Subjects/Keywords: Turbulent reacting flows; Turbulent combustion; Spray combustion; Spray flame; Combustion modelling; Reynolds-Averaged Navier-Stokes; Large-Eddy Simulation; Conditional Moment Closure; Doubly Conditional Moment Closure; RANS; LES; CMC; DCMC; Computational Fluid Dynamics; CFD; Eulerian-Lagrangian approach; Multi-phase flow; Numerical simulation
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APA ·
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MLA ·
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CSE |
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APA (6th Edition):
Sitte, M. P. (2019). Modelling of spray combustion with doubly conditional moment closure. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.39071 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.774699
Chicago Manual of Style (16th Edition):
Sitte, Michael Philip. “Modelling of spray combustion with doubly conditional moment closure.” 2019. Doctoral Dissertation, University of Cambridge. Accessed January 22, 2021.
https://doi.org/10.17863/CAM.39071 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.774699.
MLA Handbook (7th Edition):
Sitte, Michael Philip. “Modelling of spray combustion with doubly conditional moment closure.” 2019. Web. 22 Jan 2021.
Vancouver:
Sitte MP. Modelling of spray combustion with doubly conditional moment closure. [Internet] [Doctoral dissertation]. University of Cambridge; 2019. [cited 2021 Jan 22].
Available from: https://doi.org/10.17863/CAM.39071 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.774699.
Council of Science Editors:
Sitte MP. Modelling of spray combustion with doubly conditional moment closure. [Doctoral Dissertation]. University of Cambridge; 2019. Available from: https://doi.org/10.17863/CAM.39071 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.774699
23.
Sitte, Michael Philip.
Modelling of Spray Combustion with Doubly Conditional Moment Closure.
Degree: PhD, 2019, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/291915
► Turbulent spray combustion is characterised by a strong coupling of evaporation, mixing and chemical reaction. This leads to a wide spectrum of combustion regimes, where…
(more)
▼ Turbulent spray combustion is characterised by a strong coupling of evaporation, mixing and chemical reaction. This leads to a wide spectrum of combustion regimes, where self-propagating premixed flames and diffusion-controlled non-premixed flames may occur simultaneously within the same flame. The physical processes involved in spray combustion and their interaction take place over a broad range of scales, which makes their modelling in numerical simulations challenging.
This thesis presents the development of Doubly Conditional Moment Closure (DCMC) for the modelling of turbulent spray combustion. This modelling approach allows us to consider the effects of finite-rate chemistry and spray evaporation on the flame. Using a parametrisation of the flame structure, based on mixture fraction and reaction progress variable permits us to resolve premixed, non-premixed and intermediate combustion modes.
In the first part of this thesis, the model development is presented. With its foundation as a statistical model, DCMC does not require any strong assumption in terms of the combustion mode or regime. The DCMC equation is derived in a general form, which involves only a minimum number of modelling assumptions about the physical processes involved. Closure for the DCMC equation is discussed and a complete set of models is suggested. Since little experience exists in the modelling of doubly-conditional terms, the closure models were generalised from conventional Conditional Moment Closure (CMC) or adapted from other combustion models with similar parametrisation.
In the second part, the DCMC model is validated for two test flames. The DCMC model was first applied to the Cambridge spray jet flame using the Reynolds-Averaged Navier-Stokes (RANS) approach. This flame is characterised by significant pre-vaporisation and behaves as a propagating spray flame, with similarities to premixed flames, but with small-scale inhomogeneity in the gaseous mixture and the presence of liquid droplet interacting with the flame – a problem which requires the doubly-conditional description of the flame structure employed in the DCMC model. The role of the spray terms on the flame structure and mixing field were assessed using RANS and promising results were obtained.
Finally, a Large-Eddy Simulation (LES) with DCMC acting as sub-grid scale combustion model was applied to the Rouen spray jet flame. LES-DCMC was found to accurately predict the spray statistics, lift-off height and flame shape. Small-scale effects of the spray on the flame could be resolved thanks to the doubly-conditional parametrisation of the flame structure. Temporal fluctuations and spatial variations of the flame structure were investigated. Spatial gradients of the doubly-conditional flame structure were small and convective transport was found to play a minor role on the flame structure compared to the effects of micro-mixing and chemical reaction in the DCMC equation. The findings of this work suggest that, besides spray combustion, DCMC shows great…
Subjects/Keywords: Turbulent reacting flows; Turbulent combustion; Spray combustion; Spray flame; Combustion modelling; Reynolds-Averaged Navier-Stokes; Large-Eddy Simulation; Conditional Moment Closure; Doubly Conditional Moment Closure; RANS; LES; CMC; DCMC; Computational Fluid Dynamics; CFD; Eulerian-Lagrangian approach; Multi-phase flow; Numerical simulation
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
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Manager
APA (6th Edition):
Sitte, M. P. (2019). Modelling of Spray Combustion with Doubly Conditional Moment Closure. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/291915
Chicago Manual of Style (16th Edition):
Sitte, Michael Philip. “Modelling of Spray Combustion with Doubly Conditional Moment Closure.” 2019. Doctoral Dissertation, University of Cambridge. Accessed January 22, 2021.
https://www.repository.cam.ac.uk/handle/1810/291915.
MLA Handbook (7th Edition):
Sitte, Michael Philip. “Modelling of Spray Combustion with Doubly Conditional Moment Closure.” 2019. Web. 22 Jan 2021.
Vancouver:
Sitte MP. Modelling of Spray Combustion with Doubly Conditional Moment Closure. [Internet] [Doctoral dissertation]. University of Cambridge; 2019. [cited 2021 Jan 22].
Available from: https://www.repository.cam.ac.uk/handle/1810/291915.
Council of Science Editors:
Sitte MP. Modelling of Spray Combustion with Doubly Conditional Moment Closure. [Doctoral Dissertation]. University of Cambridge; 2019. Available from: https://www.repository.cam.ac.uk/handle/1810/291915
Brno University of Technology
24.
Skála, Adam.
Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru: Study of Inertial Particle Separator in a typical turboprop engine.
Degree: 2019, Brno University of Technology
URL: http://hdl.handle.net/11012/175529
► This thesis focuses on ingestion of foreign objects into standard turboprop engine GE H80 situated in aircraft Let L-410 Turbolet. Aim of this study is…
(more)
▼ This thesis focuses on ingestion of foreign objects into standard turboprop engine GE H80 situated in aircraft Let L-410 Turbolet. Aim of this study is to create methodology of numerical simulation of particle movement inside the engine, which could be used during design process of Inertial Particle Separator device. Thesis consists of backward-facing step benchmark study which validates used methodology. Second part describes flow field calculation and numerical setup. The last part is dedicated to particle tracking analysis. Simulated trajectories are visually investigated, and coordinates of particle impacts at 1st rotor of a compressor are correlated to position of real observed damage.
Advisors/Committee Members: Popela, Robert (advisor), Doupník, Petr (referee).
Subjects/Keywords: Inerční odlučovač částic; Výpočetní dynamika tekutin; CFD; Trasování částic; RANS modely turbulence; Stlačitelné proudění; Turbovrtulový motor; Inertial particle separator; Computational fluid dynamics; CFD; Particle tracking analysis; Reynolds averaged Navier-Stokes turbulence models; Compressible flow; Turboprop engine
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CSE |
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APA (6th Edition):
Skála, A. (2019). Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru: Study of Inertial Particle Separator in a typical turboprop engine. (Thesis). Brno University of Technology. Retrieved from http://hdl.handle.net/11012/175529
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Skála, Adam. “Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru: Study of Inertial Particle Separator in a typical turboprop engine.” 2019. Thesis, Brno University of Technology. Accessed January 22, 2021.
http://hdl.handle.net/11012/175529.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Skála, Adam. “Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru: Study of Inertial Particle Separator in a typical turboprop engine.” 2019. Web. 22 Jan 2021.
Vancouver:
Skála A. Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru: Study of Inertial Particle Separator in a typical turboprop engine. [Internet] [Thesis]. Brno University of Technology; 2019. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/11012/175529.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Skála A. Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru: Study of Inertial Particle Separator in a typical turboprop engine. [Thesis]. Brno University of Technology; 2019. Available from: http://hdl.handle.net/11012/175529
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Cranfield University
25.
Alimin, E. K.
Dissipation and discretization in time marching CFD calculation.
Degree: PhD, 1995, Cranfield University
URL: http://dspace.lib.cranfield.ac.uk/handle/1826/4021
;
http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309693
► This thesis concentrates on accuracy improvements for an existing software package that solves the three dimensional Reynolds Averaged Navier-Stokes equations in rotating coordinates. It is…
(more)
▼ This thesis concentrates on accuracy improvements for an existing software package that solves the three dimensional Reynolds Averaged Navier-Stokes equations in rotating coordinates. It is a cell centred explicit time marching code. Two topics are considered: improvement to the discretization scheme, and reduction of the artificial dissipation. The first topic is the analysis of the straight averaging process which demonstrates that the process can result in inconsistency with a skewed grid. An alternative consistent scheme is proposed which is based upon quadratic interpolation. Improved accuracy can also be obtained by modifying the grid or adopting a cell vertex scheme. The stability of the iterative process is also shown to depend on the time step. The reduction of artificial dissipation (second topic) first considers the role of the so called aspectratio and velocity functions. These are found to be limited in influence and a new function is proposed based upon the local flow gradient. Both two and three dimensional turbomachinery cases are tested and improvements demonstrated. In the second part of the analysis, the eigenvalues of the stability matrix are used to reduce the dissipation in overdamped regions. Again this method is applied to various test cases and improvements demonstrated. The management part of this Total Technology PhD Program discusses topics concerned with collaboration and technology development in the aero engine industry with particular emphasis on the role of an 'emerging' partner.
Subjects/Keywords: 519; Reynold Averaged Navier-Stokes equations
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APA (6th Edition):
Alimin, E. K. (1995). Dissipation and discretization in time marching CFD calculation. (Doctoral Dissertation). Cranfield University. Retrieved from http://dspace.lib.cranfield.ac.uk/handle/1826/4021 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309693
Chicago Manual of Style (16th Edition):
Alimin, E K. “Dissipation and discretization in time marching CFD calculation.” 1995. Doctoral Dissertation, Cranfield University. Accessed January 22, 2021.
http://dspace.lib.cranfield.ac.uk/handle/1826/4021 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309693.
MLA Handbook (7th Edition):
Alimin, E K. “Dissipation and discretization in time marching CFD calculation.” 1995. Web. 22 Jan 2021.
Vancouver:
Alimin EK. Dissipation and discretization in time marching CFD calculation. [Internet] [Doctoral dissertation]. Cranfield University; 1995. [cited 2021 Jan 22].
Available from: http://dspace.lib.cranfield.ac.uk/handle/1826/4021 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309693.
Council of Science Editors:
Alimin EK. Dissipation and discretization in time marching CFD calculation. [Doctoral Dissertation]. Cranfield University; 1995. Available from: http://dspace.lib.cranfield.ac.uk/handle/1826/4021 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309693
Universidade do Estado do Rio de Janeiro
26.
Hyun Ho Shin.
Uma Metodologia de Estudo de Simulação Tridimensional de Escoamento
Turbulento Estratificado no Reservatório de Plantas Hidrelétricas.
Degree: Master, 2009, Universidade do Estado do Rio de Janeiro
URL: http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8586
;
► Uma simulação numérica que leva em conta os efeitos de estratificação e mistura escalar (como a temperatura, salinidade ou substância solúvel em água) é necessária…
(more)
▼ Uma simulação numérica que leva em conta os efeitos de estratificação e mistura escalar
(como a temperatura, salinidade ou substância solúvel em água) é necessária para estudar
e prever os impactos ambientais que um reservatório de usina hidrelétrica pode produzir. Este
trabalho sugere uma metodologia para o estudo de escoamentos ambientais, principalmente
aqueles em que o conhecimento da interação entre a estratificação e mistura pode dar noções
importantes dos fenômenos que ocorrem. Por esta razão, ferramentas de simulação numérica
3D de escoamento ambiental são desenvolvidas. Um gerador de malha de tetraedros do reservatório
e o modelo de turbulência algébrico baseado no número de Richardson são as principais
ferramentas desenvolvidas. A principal dificuldade na geração de uma malha de tetraedros de
um reservatório é a distribuição não uniforme dos pontos relacionada com a relação desproporcional
entre as escalas horizontais e verticais do reservatório. Neste tipo de distribuição de
pontos, o algoritmo convencional de geração de malha de tetraedros pode tornar-se instável. Por
esta razão, um gerador de malha não estruturada de tetraedros é desenvolvido e a metodologia
utilizada para obter elementos conformes é descrita. A geração de malha superficial de triângulos
utilizando a triangulação Delaunay e a construção do tetraedros a partir da malha triangular
são os principais passos para o gerador de malha. A simulação hidrodinâmica com o modelo de
turbulência fornece uma ferramenta útil e computacionalmente viável para fins de engenharia.
Além disso, o modelo de turbulência baseado no número de Richardson leva em conta os efeitos
da interação entre turbulência e estratificação. O modelo algébrico é o mais simples entre os diversos
modelos de turbulência. Mas, fornece resultados realistas com o ajuste de uma pequena
quantidade de parâmetros. São incorporados os modelos de viscosidade/difusividade turbulenta
para escoamento estratificado. Na aproximação das equações médias de Reynolds e transporte
de escalar é utilizando o Método dos Elementos Finitos. Os termos convectivos são aproximados
utilizando o método semi-Lagrangeano, e a aproximação espacial é baseada no método
de Galerkin. Os resultados computacionais são comparados com os resultados disponíveis na
literatura. E, finalmente, a simulação de escoamento em um braço de reservatório é apresentada.
To study and forecast the environmental impacts that a hydroelectric power plant reservoir
may produce, a numerical simulation that takes into account the effects of stratification
and scalar mixing (such as temperature, salinity or water-soluble substance) is required. This
work proposes a methodology for the study of the environmental fluid flow phenomena, mainly
for flows in which the knowledge of the interaction between stratification and mixing can give
important notions of the phenomena that occur. For this, a numerical simulation tool for 3D
environmental flow is developed. A tetrahedral mesh generator of the reservoir based on the
terrain topology and an…
Advisors/Committee Members: Alvaro Luiz Gayoso de Azeredo Coutinho, Carlos Antonio de Moura, Norberto Mangiavacchi, Cassio Botelho Pereira Soares, José da Rocha Miranda Pontes, Edson Cezar Wendland, Christian Emilio Schaerer Serra.
Subjects/Keywords: Unstructured Mesh Generation; Numerical Simulation; Finite Element Method; Reynolds Averaged Navier Stokes equations;
Eddy-Viscosity/Diffusivity Models; Stratified Turbulent Flow; Geração de Malha não estruturada; Simulação Numérica; Métodos de Elementos Finitos; Equações Médias de Reynolds;
Modelo de Viscosidade/Difusividade Turbulenta; Escoamento Estratificado Turbulento; ENGENHARIA MECANICA
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APA (6th Edition):
Shin, H. H. (2009). Uma Metodologia de Estudo de Simulação Tridimensional de Escoamento
Turbulento Estratificado no Reservatório de Plantas Hidrelétricas. (Masters Thesis). Universidade do Estado do Rio de Janeiro. Retrieved from http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8586 ;
Chicago Manual of Style (16th Edition):
Shin, Hyun Ho. “Uma Metodologia de Estudo de Simulação Tridimensional de Escoamento
Turbulento Estratificado no Reservatório de Plantas Hidrelétricas.” 2009. Masters Thesis, Universidade do Estado do Rio de Janeiro. Accessed January 22, 2021.
http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8586 ;.
MLA Handbook (7th Edition):
Shin, Hyun Ho. “Uma Metodologia de Estudo de Simulação Tridimensional de Escoamento
Turbulento Estratificado no Reservatório de Plantas Hidrelétricas.” 2009. Web. 22 Jan 2021.
Vancouver:
Shin HH. Uma Metodologia de Estudo de Simulação Tridimensional de Escoamento
Turbulento Estratificado no Reservatório de Plantas Hidrelétricas. [Internet] [Masters thesis]. Universidade do Estado do Rio de Janeiro; 2009. [cited 2021 Jan 22].
Available from: http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8586 ;.
Council of Science Editors:
Shin HH. Uma Metodologia de Estudo de Simulação Tridimensional de Escoamento
Turbulento Estratificado no Reservatório de Plantas Hidrelétricas. [Masters Thesis]. Universidade do Estado do Rio de Janeiro; 2009. Available from: http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8586 ;
27.
Kress, Jessica Elaine.
The unstructured grid incompressible Navier-Stokes algorithm for convective heat transfer based on artificial compressibility.
Degree: 2012, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/44
► The development of an explicit unstructured grid finite-volume scheme for solving the full incompressible Navier-Stokes equations along with the energy equation in a strongly coupled…
(more)
▼ The development of an explicit unstructured grid finite-volume scheme for solving the
full incompressible
Navier-
Stokes equations along with the energy equation in a strongly
coupled manner is presented. The Boussinesq approximation is utilized to account for
thermal buoyancy. The method of artificial compressibilty is used to solve the resulting
equations in a time marching fashion. Roe's approximate Riemann solver is used for the
construction of the numerical flux. An eigensystem is derived for the flux Jacobian matrix,
which is used in the evaluation of the numerical flux and the characteristic variable boundary
conditions. The resulting algorithm is validated by simulating canonical test cases from the
three regimes of convective heat transfer. The computed solutions are in close agreement
with analytical solutions and other benchmark computations.
Advisors/Committee Members: Taylor, Lafayette, Hyams, Daniel, Swafford, Timothy, College of Engineering and Computer Science.
Subjects/Keywords: Navier-Stokes equations
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APA (6th Edition):
Kress, J. E. (2012). The unstructured grid incompressible Navier-Stokes algorithm for convective heat transfer based on artificial compressibility. (Masters Thesis). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/44
Chicago Manual of Style (16th Edition):
Kress, Jessica Elaine. “The unstructured grid incompressible Navier-Stokes algorithm for convective heat transfer based on artificial compressibility.” 2012. Masters Thesis, University of Tennessee – Chattanooga. Accessed January 22, 2021.
https://scholar.utc.edu/theses/44.
MLA Handbook (7th Edition):
Kress, Jessica Elaine. “The unstructured grid incompressible Navier-Stokes algorithm for convective heat transfer based on artificial compressibility.” 2012. Web. 22 Jan 2021.
Vancouver:
Kress JE. The unstructured grid incompressible Navier-Stokes algorithm for convective heat transfer based on artificial compressibility. [Internet] [Masters thesis]. University of Tennessee – Chattanooga; 2012. [cited 2021 Jan 22].
Available from: https://scholar.utc.edu/theses/44.
Council of Science Editors:
Kress JE. The unstructured grid incompressible Navier-Stokes algorithm for convective heat transfer based on artificial compressibility. [Masters Thesis]. University of Tennessee – Chattanooga; 2012. Available from: https://scholar.utc.edu/theses/44
28.
Erwin, Jon Taylor.
Stabilized finite elements for compressible turbulent Navier-Stokes.
Degree: 2013, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/94
► In this research a stabilized finite element approach is utilized in the development of a high-order flow solver for compressible turbulent flows. The Reynolds averaged…
(more)
▼ In this research a stabilized finite element approach is utilized in the development of a high-order flow solver for compressible turbulent flows. The
Reynolds averaged Navier-
Stokes (
RANS)
equations and modified Spalart-Almaras (SA) turbulence model are discretized using the streamline/upwind Petrov-Galerkin (SUPG) scheme. A fully implicit methodology is used to obtain steady state solutions or to drive unsteady problems at each time step. Order of accuracy is assessed for inviscid and viscous flows in two and three dimensions via the method of manufactured solutions. Proper treatment of curved surface geometries is of vital importance in high-order methods, especially when high aspect ratio elements are used in viscous flow regions. In two dimensions, analytic surface representations are used to ensure proper surface point placement, and an algebraic mesh smoothing procedure is applied to prevent invalid elements in high aspect ratio meshes. In dealing with complex three-dimensional geometries, high-order curved surfaces are generated via a Computational Analysis PRogramming Interface (CAPRI), while the interior meshes are deformed through a linear elasticity solver. In addition, the effects of curved elements on solution accuracy are evaluated. Finally, several test cases in two and three dimensions are presented and compared with benchmark results and/or experimental data.
Advisors/Committee Members: Anderson, W. Kyle, Kapadia, Sagar, Wang, Li, Sreenivas, Kidambi, College of Engineering and Computer Science.
Subjects/Keywords: Navier-Stokes equations
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MLA ·
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CSE |
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APA (6th Edition):
Erwin, J. T. (2013). Stabilized finite elements for compressible turbulent Navier-Stokes. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/94
Chicago Manual of Style (16th Edition):
Erwin, Jon Taylor. “Stabilized finite elements for compressible turbulent Navier-Stokes.” 2013. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed January 22, 2021.
https://scholar.utc.edu/theses/94.
MLA Handbook (7th Edition):
Erwin, Jon Taylor. “Stabilized finite elements for compressible turbulent Navier-Stokes.” 2013. Web. 22 Jan 2021.
Vancouver:
Erwin JT. Stabilized finite elements for compressible turbulent Navier-Stokes. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2013. [cited 2021 Jan 22].
Available from: https://scholar.utc.edu/theses/94.
Council of Science Editors:
Erwin JT. Stabilized finite elements for compressible turbulent Navier-Stokes. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2013. Available from: https://scholar.utc.edu/theses/94
University of New Mexico
29.
Payne, Michael.
A Study of the Pressure Term in the Navier-Stokes Equations.
Degree: Mathematics & Statistics, 2013, University of New Mexico
URL: http://hdl.handle.net/1928/23360
► In this paper we consider the Cauchy problem for the 3D \\NS equations for incompressible flows, and their solutions. We will discuss the results of…
(more)
▼ In this paper we consider the Cauchy problem for the 3D \\NS
equations for incompressible flows, and their solutions. We will discuss the results of a paper by Otto Kreiss and Jens Lorenz on the role of the pressure term in the \\NS
equations, and its relationship to the fluid field u(x,t). The focus here is to concentrate on solutions to the equation where the fluid field u lies in the space \\Ci(\\R
3)\\cap\\Li(\\R
3), and not necessarily in L
2(\\R
3). If u(x,0)=f(x), where f\∈\\Ci(\\R
3)\\cap\\Li(\\R
3) we will consider the solutions for all t in time interval 0\ ≤ t < T(f). In the original paper, estimates for the \\emph{derivatives} of the pressure were proved, but the definition of the pressure proved unsatisfactory due to the possibility of the divergence of the pressure term. The main object of this paper is to use the theory of singular integrals and the space of functions of \\BMO to properly address the pressure. In doing so, we will provide estimates on pressure term itself. This will allow us to strengthen the results of the original paper, and rigorously extend all results from the original paper to \\emph{any} function u\∈\\Ci(\\R
3)\\cap\\Li(\\R
3).
Advisors/Committee Members: Lorenz, Jens, Pereyra, Cristina, Appelo, Daniel, Sorrentino, Francesco.
Subjects/Keywords: Navier Stokes Equations
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APA ·
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APA (6th Edition):
Payne, M. (2013). A Study of the Pressure Term in the Navier-Stokes Equations. (Doctoral Dissertation). University of New Mexico. Retrieved from http://hdl.handle.net/1928/23360
Chicago Manual of Style (16th Edition):
Payne, Michael. “A Study of the Pressure Term in the Navier-Stokes Equations.” 2013. Doctoral Dissertation, University of New Mexico. Accessed January 22, 2021.
http://hdl.handle.net/1928/23360.
MLA Handbook (7th Edition):
Payne, Michael. “A Study of the Pressure Term in the Navier-Stokes Equations.” 2013. Web. 22 Jan 2021.
Vancouver:
Payne M. A Study of the Pressure Term in the Navier-Stokes Equations. [Internet] [Doctoral dissertation]. University of New Mexico; 2013. [cited 2021 Jan 22].
Available from: http://hdl.handle.net/1928/23360.
Council of Science Editors:
Payne M. A Study of the Pressure Term in the Navier-Stokes Equations. [Doctoral Dissertation]. University of New Mexico; 2013. Available from: http://hdl.handle.net/1928/23360
Rutgers University
30.
Yan, Xukai, 1987-.
Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere.
Degree: PhD, Mathematics, 2017, Rutgers University
URL: https://rucore.libraries.rutgers.edu/rutgers-lib/54047/
► We classify all (-1)-homogeneous axisymmetric no-swirl solutions of incompressible stationary Navier-Stokes equations in three dimension which are smooth on the unit sphere minus the south…
(more)
▼ We classify all (-1)-homogeneous axisymmetric no-swirl solutions of incompressible stationary Navier-Stokes equations in three dimension which are smooth on the unit sphere minus the south and north poles. We establish existence and nonexistence results of (-1)-homogeneous axisymmetric solutions with nonzero swirl emamnating from axisymmetric no-swirl solutions. We also establish asymptotic expansions for every (-1)-homogeneous axisymmetric solutions in a neighborhood of a singular point on the unit sphere.
Advisors/Committee Members: Li, YanYan (chair), Han, Zhengchao (internal member), Carlen, Eric (internal member), Sverak, Vladimir (outside member).
Subjects/Keywords: Navier-Stokes equations
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APA ·
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MLA ·
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CSE |
Export
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Manager
APA (6th Edition):
Yan, Xukai, 1. (2017). Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere. (Doctoral Dissertation). Rutgers University. Retrieved from https://rucore.libraries.rutgers.edu/rutgers-lib/54047/
Chicago Manual of Style (16th Edition):
Yan, Xukai, 1987-. “Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere.” 2017. Doctoral Dissertation, Rutgers University. Accessed January 22, 2021.
https://rucore.libraries.rutgers.edu/rutgers-lib/54047/.
MLA Handbook (7th Edition):
Yan, Xukai, 1987-. “Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere.” 2017. Web. 22 Jan 2021.
Vancouver:
Yan, Xukai 1. Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere. [Internet] [Doctoral dissertation]. Rutgers University; 2017. [cited 2021 Jan 22].
Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/54047/.
Council of Science Editors:
Yan, Xukai 1. Homogeneous solutions of stationary Navier-Stokes equations with isolated singularities on the unit sphere. [Doctoral Dissertation]. Rutgers University; 2017. Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/54047/
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Open Access Theses and Dissertations
