+publisher:"Clemson University" +contributor:("Tong , Chenning")

Clemson University

1. Liu, Shuaishuai. INVESTIGATION OF SUBGRID-SCALE MIXING IN TURBULENT PLANE JETS AND TURBULENT JET FLAMES.

Degree: PhD, Mechanical Engineering, 2014, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/1421

► The subgrid-scale (SGS) mixing of mixture fraction, temperature, and species mass fraction in turbulent partially premixed (Sandia) flames is studied. We focus on the… (more)

▼ The subgrid-scale (SGS) mixing of mixture fraction, temperature, and species mass fraction in turbulent partially premixed (Sandia) flames is studied. We focus on the effects of the SGS mixing regimes and the spatial relationships among the scalars on the SGS mixing of the species mass fractions. High resolution lines images are used to obtain the scalar filtered mass density function and the conditionally filtered diffusion. The results show that for small SGS variance the scalar fields have a relatively simple structure. For large SGS variance the structure is more complex. The spatial relationships among the scalars result in different SGS scalar structures and SGS mixing characteristics, with the mass fraction of CO2 being the simplest and that of CO being the most complex. The results in this study present a challenging test for SGS mixing models. Recent studies of subgrid-scale (SGS) mixing and turbulence-chemistry interaction have shown that turbulent flames contain different structures. In flamelets diffusion of reactive scalars and chemical reaction are tightly coupled. Most mixing models used in probability density and filtered density methods, however, are based on non-reactive scalars. To investigate the effects of the coupling on the diffusion we decompose a reactive scalar into a steady flamelet part and perturbations from it. The diffusion of the former can be obtained from a flamelet solution while the latter is unclosed. The conditionally filtered diffusion and dissipation of the reactive scalar perturbations are analyzed using high-resolution line images obtained in turbulent partially premixed (Sandia) flames. For SGS scalar containing flamelets, the perturbation diffusion has characteristics similar to that of a non-reactive scalar, in contrast with the flamelet part. The functional form of the conditionally filtered diffusion is well described by the Interaction by Exchange with the Mean (IEM) model. Our perturbation analysis of the flamelet equation shows that for perturbations having length scales smaller than the reaction zone width, the reactive scalar diffusion are largely controlled by the mixture fraction field, thus have the characteristics of non-reactive scalar mixing. For perturbations with length scales larger than the reaction width, the conditionally filtered diffusion has the same form as non-reactive scalar mixing, with the mixing time scale given by the flamelet. The IEM model predictions based on this mixing time scale are in good agreement with the experimental results for a range of SGS conditions, suggesting that the perturbations for the conditions studied are consistent with unsteady flamelets. Thus, mixing models based on non-reactive scalars can potentially model the SGS mixing accurately. The results in the present study can be useful for developing a unified mixing model that can predict all combustion regimes accurately. There already have extensive studies about turbulent mixing based on two-scalars. However, in many applications such as reactive flows, at least… Advisors/Committee Members: Tong, Chenning, Miller , Richard, Xuan , Xiangchun, Ochterbeck , Jay.

Subjects/Keywords: turbulent combustion; turbulent mixing; Mechanical Engineering

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APA (6^th Edition):

Liu, S. (2014). INVESTIGATION OF SUBGRID-SCALE MIXING IN TURBULENT PLANE JETS AND TURBULENT JET FLAMES. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/1421

Chicago Manual of Style (16^th Edition):

Liu, Shuaishuai. “INVESTIGATION OF SUBGRID-SCALE MIXING IN TURBULENT PLANE JETS AND TURBULENT JET FLAMES.” 2014. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/1421.

MLA Handbook (7^th Edition):

Liu, Shuaishuai. “INVESTIGATION OF SUBGRID-SCALE MIXING IN TURBULENT PLANE JETS AND TURBULENT JET FLAMES.” 2014. Web. 11 Apr 2021.

Vancouver:

Liu S. INVESTIGATION OF SUBGRID-SCALE MIXING IN TURBULENT PLANE JETS AND TURBULENT JET FLAMES. [Internet] [Doctoral dissertation]. Clemson University; 2014. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/1421.

Council of Science Editors:

Liu S. INVESTIGATION OF SUBGRID-SCALE MIXING IN TURBULENT PLANE JETS AND TURBULENT JET FLAMES. [Doctoral Dissertation]. Clemson University; 2014. Available from: https://tigerprints.clemson.edu/all_dissertations/1421

Clemson University

2. Chenna, Varun. Fatigue-Induced Failure in Horizontal-Axis Wind-Turbine (HAWT) Blades and HAWT Drivetrain Gears.

Degree: MS, Mechanical Engineering, 2014, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/1863

► Wind energy is one of the most promising and the fastest growing installed alternative-energy production technologies. In fact, it is anticipated that by 2030,… (more)

▼ Wind energy is one of the most promising and the fastest growing installed alternative-energy production technologies. In fact, it is anticipated that by 2030, at least 20% of the U.S. energy needs will be met by various onshore and offshore wind-farms [a collection of wind-turbines (converters of wind energy into electrical energy) at the same location]. A majority of wind turbines nowadays fall into the class of the so-called Horizontal Axis Wind Turbines (HAWTs). Turbine blades and the gearbox are perhaps the most critical components/subsystems in the present designs of HAWTs. The combination of high failure rates (particularly those associated with turbine-blades and gear-boxes), long downtimes and the high cost of repair remains one of the major problems to the wind-energy industry today. In the case of HAWT blades, one is typically concerned about the following two quasi-static structural-performance requirements: (a) sufficient 'flap-wise' bending strength to withstand highly-rare extreme static-loading conditions (e.g., 50-year return-period gust, a short strong blast of wind); and (b) sufficient turbine blade 'flap-wise' bending stiffness in order to ensure that a minimal clearance is maintained between blade tip and the turbine tower at all times during wind turbine operation. If these two structural requirements are not met, HAWT blades typically fail prematurely. In addition to the aforementioned quasi-static structural-performance requirements, one is also concerned about the premature-failure caused by inadequate fatigue-based durability of the HAWT blades. The durability requirement for the turbine blades is typically defined as a minimum of 20-year fatigue life (which corresponds roughly to ca. 108 cycles) when subjected to stochastic wind-loading conditions and cyclic gravity-induced edge-wise bending loads in the presence of thermally-fluctuating and environmentally challenging conditions. In the present work, a computational framework has been developed to address: (a) structural response of HAWT blades subjected to extreme loading conditions; (b) high-cycle-fatigue-controlled durability of the HAWT blades; and (c) methodology for HAWT-blade material selection. To validate the computational approach used, key results are compared with their experimental counterparts available in the public-domain literature. As far as the HAWT gear-boxes are concerned, while they are designed for the entire life (ca. 20 years) of the HAWT, in practice, most gear-boxes have to be repaired or even overhauled considerably earlier (3-5 years). Typically, a HAWT gear-box fails either due to the bending-fatigue-induced failure of its gears, or by tribo-chemical degradation and failure of its bearings. In the present work, a computational framework has been developed to predict HAWT service-life under extreme loading and unfavorable kinematic conditions, for the case when the gear-box service-life is controlled by gear-tooth bending-fatigue failure. In addition, a preliminary investigation of gear-box bearing… Advisors/Committee Members: Grujicic, Mica, Tong , Chenning, Ochterbeck , Jay.

Subjects/Keywords: Fatigue Life Assessment; Finite Element Analysis; Gearbox Reliability; Horizontal-Axis Wind-Turbine; Material Selection; Multi-Body Dynamics; Mechanical Engineering

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APA (6^th Edition):

Chenna, V. (2014). Fatigue-Induced Failure in Horizontal-Axis Wind-Turbine (HAWT) Blades and HAWT Drivetrain Gears. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/1863

Chicago Manual of Style (16^th Edition):

Chenna, Varun. “Fatigue-Induced Failure in Horizontal-Axis Wind-Turbine (HAWT) Blades and HAWT Drivetrain Gears.” 2014. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/1863.

MLA Handbook (7^th Edition):

Chenna, Varun. “Fatigue-Induced Failure in Horizontal-Axis Wind-Turbine (HAWT) Blades and HAWT Drivetrain Gears.” 2014. Web. 11 Apr 2021.

Vancouver:

Chenna V. Fatigue-Induced Failure in Horizontal-Axis Wind-Turbine (HAWT) Blades and HAWT Drivetrain Gears. [Internet] [Masters thesis]. Clemson University; 2014. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/1863.

Council of Science Editors:

Chenna V. Fatigue-Induced Failure in Horizontal-Axis Wind-Turbine (HAWT) Blades and HAWT Drivetrain Gears. [Masters Thesis]. Clemson University; 2014. Available from: https://tigerprints.clemson.edu/all_theses/1863

Clemson University

3. Zeng, Jian. MAGNETIC MANIPULATION OF PARTICLES AND CELLS IN FERROFLUID FLOW THROUGH STRAIGHT MICROCHANNELS USING TWO MAGNETS.

Degree: MS, Mechanical Engineering, 2013, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/1632

► Microfluidic devices have been increasingly used in the past two decades for particle and cell manipulations in many chemical and biomedical applications. A variety… (more)

▼ Microfluidic devices have been increasingly used in the past two decades for particle and cell manipulations in many chemical and biomedical applications. A variety of force fields have been demonstrated to control particle and cell transport in these devices including electric, magnetic, acoustic, and optical forces etc. Among these particle handling techniques, the magnetic approach provides clear advantages over others such as low cost, noninvasive, and free of fluid heating issues. However, the current knowledge of magnetic control of particle transport is still very limited, especially lacking is the handling of diamagnetic particle. This thesis is focused on the magnetic manipulation of diamagnetic particles and cells in ferrofluid flow through the use of a pair of permanent magnets. By varying the configuration of the two magnets, diverse operations of particles and cells is implemented in a straight microchannel that can potentially be integrated into lab-on-a-chip devices for various applications. First, an approach for embedding two, symmetrically positioned, repulsive permanent magnets about a straight rectangular microchannel in a PDMS-based microfluidic device is developed for particle focusing. Focusing particles and cells into a tight stream is often required in order for continuous detection, counting, and sorting. The closest distance between the magnets is limited only by the size of the magnets involved in the fabrication process. The device is used to implement and investigate the three-dimensional magnetic focusing of polystyrene particles in ferrofluid microflow with both top-view and side-view visualizations. The effects of flow speed and particle size on the particle focusing effectiveness are studied. This device is also applied to magnetically focus yeast cells in ferrofluid, which proves to be biocompatible as verified by cell viability test. In addition, an analytical model is developed and found to be able to predict the experimentally observed particle and cell focusing behaviors with reasonable agreement. Next, a simple magnetic technique to concentrate polystyrene particles and live yeast cells in ferrofluid flow through a straight rectangular microchannel is developed. Concentrating particles to a detectable level is often necessary in many applications. The magnetic field gradient is created by two attracting permanent magnets that are placed on the top and bottom of the planar microfluidic device and held in position by their natural attractive force. The effects of flow speed and magnet-magnet distance are studied and the device was applied for use for concentrating live yeast cells. The magnet-magnet distance is mainly controlled by the thickness of the device substrate and can be made small, providing a locally strengthened magnetic field as well as allowing for the use of dilute ferrofluid in the developed magnetic concentration technique. This advantage not only enables a magnetic/fluorescent label-free handling of diamagnetic particles but also renders such… Advisors/Committee Members: Xuan, Xiangchun, Ochterbeck, Jay, Tong, Chenning.

Subjects/Keywords: Ferrofluid; Lab-on-a-chip; Magnetic; Magnetophoresis; Microfluidics; Mechanical Engineering

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APA (6^th Edition):

Zeng, J. (2013). MAGNETIC MANIPULATION OF PARTICLES AND CELLS IN FERROFLUID FLOW THROUGH STRAIGHT MICROCHANNELS USING TWO MAGNETS. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/1632

Chicago Manual of Style (16^th Edition):

Zeng, Jian. “MAGNETIC MANIPULATION OF PARTICLES AND CELLS IN FERROFLUID FLOW THROUGH STRAIGHT MICROCHANNELS USING TWO MAGNETS.” 2013. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/1632.

MLA Handbook (7^th Edition):

Zeng, Jian. “MAGNETIC MANIPULATION OF PARTICLES AND CELLS IN FERROFLUID FLOW THROUGH STRAIGHT MICROCHANNELS USING TWO MAGNETS.” 2013. Web. 11 Apr 2021.

Vancouver:

Zeng J. MAGNETIC MANIPULATION OF PARTICLES AND CELLS IN FERROFLUID FLOW THROUGH STRAIGHT MICROCHANNELS USING TWO MAGNETS. [Internet] [Masters thesis]. Clemson University; 2013. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/1632.

Council of Science Editors:

Zeng J. MAGNETIC MANIPULATION OF PARTICLES AND CELLS IN FERROFLUID FLOW THROUGH STRAIGHT MICROCHANNELS USING TWO MAGNETS. [Masters Thesis]. Clemson University; 2013. Available from: https://tigerprints.clemson.edu/all_theses/1632

Clemson University

4. Ewing, David. An Investigation of the Application of Phase Change Materials in Practical Thermal Management Systems.

Degree: PhD, Mechanical Engineering, 2011, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/820

► This work investigates the application of alternative cooling techniques to thermal management. In the first section, this work presents models and extensive simulation studies on… (more)

Subjects/Keywords: Phase change materials; Temperature parallel simulated annealing; Wavelength multiplexed laser extinction; Mechanical Engineering

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APA (6^th Edition):

Ewing, D. (2011). An Investigation of the Application of Phase Change Materials in Practical Thermal Management Systems. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/820

Chicago Manual of Style (16^th Edition):

Ewing, David. “An Investigation of the Application of Phase Change Materials in Practical Thermal Management Systems.” 2011. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/820.

MLA Handbook (7^th Edition):

Ewing, David. “An Investigation of the Application of Phase Change Materials in Practical Thermal Management Systems.” 2011. Web. 11 Apr 2021.

Vancouver:

Ewing D. An Investigation of the Application of Phase Change Materials in Practical Thermal Management Systems. [Internet] [Doctoral dissertation]. Clemson University; 2011. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/820.

Council of Science Editors:

Ewing D. An Investigation of the Application of Phase Change Materials in Practical Thermal Management Systems. [Doctoral Dissertation]. Clemson University; 2011. Available from: https://tigerprints.clemson.edu/all_dissertations/820

Clemson University

5. Zhu, Junjie. ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS.

Degree: PhD, Mechanical Engineering, 2011, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/749

► The investigation of electrokinetic particle transport in confined microchannels has practical significances in a variety of applications ranging from traditional gel electrophoresis to electrokinetic microfluidics-based… (more)

▼ The investigation of electrokinetic particle transport in confined microchannels has practical significances in a variety of applications ranging from traditional gel electrophoresis to electrokinetic microfluidics-based lab-on-a-chip devices. To date, however, studies on particle electrokinetics have been limited to primarily theoretical or numerical analyses in straight microchannels of simple geometries. Very little work has been done on electrokinetic particle motions in real microchannels which usually consist of one or multiple turns. This thesis is dedicated to the fundamental and applied studies of electrokinetic transport and manipulation of particles in various curved microchannels using a combined experimental, theoretical, and numerical method. First, a fundamental study of particle electrokinetics in a microchannel U-turn, a typical unit in LOC devices, was investigated. A 2-D numerical model based on finite element method was developed to understand and predict the particle motion within the U-turn. It is demonstrated that particles are deflected to the outer wall of the turn by curvature-induced dielectrophoresis (termed cDEP) due to the locally intrinsic electric field gradients. Moreover, this lateral displacement increases with the rise of either the applied electric field or the particle size. Next, we utilize the cDEP in microchannel turns to implement a continuous electrokinetic focusing of particles in serpentine microchannels. Particles are demonstrated to gradually migrate to the centerline due to the periodically switched dielectrophoretic force they experience in a serpentine microchannel. This electrokinetic focusing favors large electric fields and large particles, and also increases when the number of serpentine periods increases. Such focusing also takes place in a spiral microchannel, where, however, particles are eventually focused to a stream flowing near the outer sidewall of the channel. Then, we explore the applications of cDEP to continuous electrokinetic separation of particles in curved microchannels. We develop two different approaches based on what we have acquired from the studies of particle electrokinetics in serpentine and spiral microchannels. The first approach employs a sheath flow to focus particles to one sidewall of a serpentine microchannel, where particles are then deflected to different flow paths by cDEP and thus sorted at the exit of serpentine section. We use this method to separate particles and cells by size at low DC electric fields. The second approach eliminates the sheath flow focusing of particles by the use of particle deflection and focusing in a double-spiral microchannel. Specifically, particles are focused by cDEP to one single stream near the outer wall of the first spiral, which is then displaced by cDEP and divided into two or more sub-streams in the second spiral, enabling the continuous sorting. We use this approach to implement the separation of particles by size and by charge, respectively. Moreover, we… Advisors/Committee Members: Xuan, Xiangchun, Tong , Chenning, Miller , Richard, Qiao , Rui.

Subjects/Keywords: CURVATURE-INDUCED; DIELECTROPHORESIS; ELECTROKINETIC; ELECTROPHORESIS; MICROCHANNEL; Mechanical Engineering

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APA (6^th Edition):

Zhu, J. (2011). ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/749

Chicago Manual of Style (16^th Edition):

Zhu, Junjie. “ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS.” 2011. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/749.

MLA Handbook (7^th Edition):

Zhu, Junjie. “ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS.” 2011. Web. 11 Apr 2021.

Vancouver:

Zhu J. ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS. [Internet] [Doctoral dissertation]. Clemson University; 2011. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/749.

Council of Science Editors:

Zhu J. ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS. [Doctoral Dissertation]. Clemson University; 2011. Available from: https://tigerprints.clemson.edu/all_dissertations/749

Clemson University

6. Zhao, Yan. MIXTURE FRACTION IMAGING BASED ON PHOTODISSOCIATION SPECTROSCOPY AND TWO PHOTON LASER INDUCED FLUORESCENCE.

Degree: PhD, Mechanical Engineering, 2011, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/807

► The study of turbulent combustion calls for new diagnostics that can measure multidimensional mixture fraction under a wide range of flame conditions. A laser diagnostic… (more)

▼ The study of turbulent combustion calls for new diagnostics that can measure multidimensional mixture fraction under a wide range of flame conditions. A laser diagnostic technique based on photodissociation spectroscopy (PDS) is proposed to address this need. This thesis describes the concept of the PDS-based diagnostic, reports its experimental demonstration in a non-premixed jet flame, and assesses its performance and applicable range. The two-photon laser induced fluorescence (TPLIF) technique used in conjugate with the PDS is analyzed numerically in line and planar imaging configuration. The new mixture fraction imaging technique is centered around the creative use of photodissociation (PD) for flow visualization. A carefully chosen PD precursor is seeded into the flow of interest to measure mixture fraction. The precursor is chosen such that 1) both the precursor itself and the products formed from the precursor (if it reacts) can be completely and rapidly photodissociated; thus one of the photofragments forms a conserved scalar and can be used to infer the mixture fraction, and 2) the target photofragment offers friendly spectroscopic properties (e.g., strong laser induced fluorescence signals and/or simple signal interpretation) so multidimensional imaging can be readily obtained. Molecular iodine (I2) was identified as a precursor satisfying both requirements and was seeded into a carbon monoxide (CO)/air jet flame for single-shot two-dimensional imaging of mixture fraction. This demonstration illustrates the potential of the PDS-based technique to overcome the limitations of existing techniques, and to provide multidimensional measurements of mixture fraction in a variety of reactive flows. The thesis also analyzes the imaging applications of TPLIF, which is a promising technique in the planar imaging of mixture fraction. Models are developed based on rate equation approximations and Monte Carlo simulation, with a focus on the effect of amplified spontaneous emission (ASE) on TPLIF signal interpretation. Results obtained are expected to also enhance the accuracy and applicable range of TPLIF technique in other flow imaging applications, beyond the mixture fraction imaging considered in this research. Advisors/Committee Members: Ma, Lin, Beasley , Donald E, Miller , Richard S, Tong , Chenning.

Subjects/Keywords: Mechanical Engineering

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APA (6^th Edition):

Zhao, Y. (2011). MIXTURE FRACTION IMAGING BASED ON PHOTODISSOCIATION SPECTROSCOPY AND TWO PHOTON LASER INDUCED FLUORESCENCE. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/807

Chicago Manual of Style (16^th Edition):

Zhao, Yan. “MIXTURE FRACTION IMAGING BASED ON PHOTODISSOCIATION SPECTROSCOPY AND TWO PHOTON LASER INDUCED FLUORESCENCE.” 2011. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/807.

MLA Handbook (7^th Edition):

Zhao, Yan. “MIXTURE FRACTION IMAGING BASED ON PHOTODISSOCIATION SPECTROSCOPY AND TWO PHOTON LASER INDUCED FLUORESCENCE.” 2011. Web. 11 Apr 2021.

Vancouver:

Zhao Y. MIXTURE FRACTION IMAGING BASED ON PHOTODISSOCIATION SPECTROSCOPY AND TWO PHOTON LASER INDUCED FLUORESCENCE. [Internet] [Doctoral dissertation]. Clemson University; 2011. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/807.

Council of Science Editors:

Zhao Y. MIXTURE FRACTION IMAGING BASED ON PHOTODISSOCIATION SPECTROSCOPY AND TWO PHOTON LASER INDUCED FLUORESCENCE. [Doctoral Dissertation]. Clemson University; 2011. Available from: https://tigerprints.clemson.edu/all_dissertations/807

Clemson University

7. He, Ping. Fluid Dynamics of Cell Printing.

Degree: PhD, Mechanical Engineering, 2011, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/727

► Cell printing is an emerging technology that uses droplets to deliver cells to desired positions with resolution potentially comparable to the size of single… (more)

▼ Cell printing is an emerging technology that uses droplets to deliver cells to desired positions with resolution potentially comparable to the size of single cells. In particular, ink–jet based cell printing technique has been successfully used to build simple bio–constructs and has shown a promise in building complex bio–structures or even organs. Two important issues in ink–jet based cell printing are the moderate survival rate of delicate cells and the limited cell placement resolution. Resolving these issues is critical for the ink–jet based cell printing techniques to realize their full potential. In this work, we use numerical simulations to reconstruct the impact of a droplet loaded with a single cell onto a pool of viscous fluids to gain insights into the droplet and cell dynamics during cell printing. We developed a mathematical model for this process: the droplet, pool and air are modeled as Newtonian fluids, and their flow is modeled as a laminar flow governed by the Navier–Stokes equation. The cell is modeled as an axisymmetric solid object governed by the neo–Hookean law and also has a shear viscosity that is the same as that of its host droplet. To numerically solve the coupled fluid and cell motion, we used a hybrid method in which fluid flow is solved on a fixed Cartesian grid and the deformation of solid body is solved on a Lagrangian mesh. We also developed a new full Eulerian method, termed the solid level set (SLS) method, to simulate cell printing. The key idea is to track the deformation of the solid body using four level set functions on a fixed Cartesian grid instead of using a Lagrangian mesh. The SLS method is easy to implement and addresses several challenges in simulations of fluid–tructure interactions using hybrid Eulerian/Lagrangian meshes. Using codes developed based on the above methods, we systematically investigated the fluid and cell dynamics during the cell printing process. We studied how the droplet penetration depth, droplet lateral spreading, cell stress and cell surface area change are affected by printing conditions such as impact velocity, pool depth, and cell stiffness. Our simulations indicate that cell experiences significant stress (∼20kPa) and local surface area dilation (∼100%) during the impact process. The latter suggests that cell membrane is temporally ruptured during the printing process, and is consistent with the gene transfection observed during cell printing. We speculate that the survival of cell through the rather violent cell printing process may be related to the briefness of the impact process, which only lasts about 0.1 milliseconds. Based on our simulation results, several strategies have been proposed to reduce the stress and membrane dilation of cells during cell printing. Advisors/Committee Members: Qiao, Rui, Tong , Chenning, Miller , Richard S, Zumbrunnen , David A.

Subjects/Keywords: cell printing; computational fluid dynamics; droplet impact; fluid struture interactions; multi-phase flow; Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

He, P. (2011). Fluid Dynamics of Cell Printing. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/727

Chicago Manual of Style (16^th Edition):

He, Ping. “Fluid Dynamics of Cell Printing.” 2011. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/727.

MLA Handbook (7^th Edition):

He, Ping. “Fluid Dynamics of Cell Printing.” 2011. Web. 11 Apr 2021.

Vancouver:

He P. Fluid Dynamics of Cell Printing. [Internet] [Doctoral dissertation]. Clemson University; 2011. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/727.

Council of Science Editors:

He P. Fluid Dynamics of Cell Printing. [Doctoral Dissertation]. Clemson University; 2011. Available from: https://tigerprints.clemson.edu/all_dissertations/727

Clemson University

8. HANG, TIANQI. IN VITRO MULTI-SCALE PATIENT-SPECIFIC MODELING OF HEMODYNAMICS IN STAGE 1 NORWOOD PALLIATION FOR THE TREATMENT OF SINGLE VENTRICLE HEART DISEASE.

Degree: PhD, Mechanical Engineering, 2015, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/1556

► Hypoplastic left heart syndrome (HLHS) is a congenital heart defect in which the left ventricle is severely underdeveloped. The Norwood procedure is the first stage… (more)

▼ Hypoplastic left heart syndrome (HLHS) is a congenital heart defect in which the left ventricle is severely underdeveloped. The Norwood procedure is the first stage procedure to make an unrestrictive systemic blood flow and at the same time balance it with the pulmonary flow. This is done by constructing a neo-aorta using the pulmonary artery root and the autologous aorta, and then installing a shunt to the pulmonary artery. Variations of the Norwood surgery include the modified Blalock-Taussig (mBT) shunt, which diverts blood from the innominate artery to the pulmonary artery (PA), and the Right Ventricle Shunt (RVS), which diverts blood from the right ventricle to the PA. Recurrent neo-aortic coarctation (NAO) is a frequent complication of the Norwood procedure. It causes changes in circulation flow rate balances and hypertension in the aortic arch. Conventionally, the value of a coarctation index (CoI) is used in choosing interventions to treat NAO. Aortic arch morphology of Norwood patients is suspected to be a factor of hemodynamic response to NAO. This study aims to develop and validate an in vitro model of the Norwood circulation and to use it to better understand the hemodynamic impact of progressive coarctation severity in the Norwood patients with mBT and RVS shunts. Five patient-specific cases were selected, each case having a different aortic morphology. A multi-scale mock circulatory system (MCS) was developed to simulate patient-specific Norwood circulation. The MCS couples a lumped parameter network (LPN) model of the circulation with the 3D test section of the aorta and superior arteries. The system includes branches for the pulmonary, upper body, lower body and single ventricle. The MCS was set to patient specific conditions based on the clinical measurements. Flow rate and pressure measurements were made around the circulation model. The native arch anatomy of each patient was morphed to simulate coarctation by controlling the amount of narrowing of the aortic isthmus, while keeping the original patient-specific aortic geometry intact. Separate NAO models were created to provide for a range of CoI. Aortic pressure measurements were made to study pressure drop and recovery effects. In a further study, the MCS was modified to simulate the Norwood circulation with RVS. The NAO models were used to study coarctation effects. The MCS was validated against clinical measurements. The experimental measurements demonstrated that the time-based flow rate and pressure developed within the circulation recapitulated clinical measurements (0.72 < R2 < 0.95). The results showed good fidelity in replicating the mean values of the Norwood circulation at the patient-specific level (p > 0.10). The system demonstrated the coarctation effects in the Norwood circulation with mBT. For all patient cases, the single ventricle power (SVP), mean pressure difference, and Qp/Qs increased noticeably when CoI < 0.5 (p<0.05). An increased SVP correlated with abnormal aortic arch morphology… Advisors/Committee Members: Figliola, Ricahrd S, Hsia, Tain-Yen, Beasley, Donald E, Tong, Chenning.

Subjects/Keywords: Coarctation; Mock Circulatory System; Multi-scale Modelling; Norwood Circulation; Patient-specific; Right Ventricle Shunt; Mechanical Engineering

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APA (6^th Edition):

HANG, T. (2015). IN VITRO MULTI-SCALE PATIENT-SPECIFIC MODELING OF HEMODYNAMICS IN STAGE 1 NORWOOD PALLIATION FOR THE TREATMENT OF SINGLE VENTRICLE HEART DISEASE. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/1556

Chicago Manual of Style (16^th Edition):

HANG, TIANQI. “IN VITRO MULTI-SCALE PATIENT-SPECIFIC MODELING OF HEMODYNAMICS IN STAGE 1 NORWOOD PALLIATION FOR THE TREATMENT OF SINGLE VENTRICLE HEART DISEASE.” 2015. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/1556.

MLA Handbook (7^th Edition):

HANG, TIANQI. “IN VITRO MULTI-SCALE PATIENT-SPECIFIC MODELING OF HEMODYNAMICS IN STAGE 1 NORWOOD PALLIATION FOR THE TREATMENT OF SINGLE VENTRICLE HEART DISEASE.” 2015. Web. 11 Apr 2021.

Vancouver:

HANG T. IN VITRO MULTI-SCALE PATIENT-SPECIFIC MODELING OF HEMODYNAMICS IN STAGE 1 NORWOOD PALLIATION FOR THE TREATMENT OF SINGLE VENTRICLE HEART DISEASE. [Internet] [Doctoral dissertation]. Clemson University; 2015. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/1556.

Council of Science Editors:

HANG T. IN VITRO MULTI-SCALE PATIENT-SPECIFIC MODELING OF HEMODYNAMICS IN STAGE 1 NORWOOD PALLIATION FOR THE TREATMENT OF SINGLE VENTRICLE HEART DISEASE. [Doctoral Dissertation]. Clemson University; 2015. Available from: https://tigerprints.clemson.edu/all_dissertations/1556

Clemson University

9. Nguyen, Khuong. On subgrid-scale physics in the convective atmospheric surface layer.

Degree: PhD, Mechanical Engineering, 2015, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/1600

► The dynamics of the subgrid-scale (SGS) stress and scalar flux in the convective atmospheric surface layer are studied using field measurements from the Advection Horizontal… (more)

▼ The dynamics of the subgrid-scale (SGS) stress and scalar flux in the convective atmospheric surface layer are studied using field measurements from the Advection Horizontal Array Turbulence Study (AHATS). We extend the array technique previously used to evaluate the SGS velocity and temperature to include measurements of the fluctuating pressure, enabling separation of the resolvable- and subgrid-scale pressure and allowing for the first-ever observations of the pressure covariance terms and the full SGS budgets. Non-dimensional forms of the budget terms are analysed as functions of the surface-layer stability parameter and the ratio of the wavelength of the spectral peak of the vertical velocity to the filter width, the latter a measure of the large-eddy simulation (LES) fidelity. Analyses of the mean SGS turbulence kinetic energy budget show a balance among the production, transport, and dissipation. The mean SGS shear stress and SGS temperature flux budgets, meanwhile, are dominated by the production and pressure destruction, with the latter causing return to isotropy. The budgets of the normal components of the SGS stress are more complex. Most notably the pressure-rate-of-strain includes two competing processes, return to isotropy and generation of anisotropy, the latter due to ground blockage of the large-scale convective eddies. For neutral surface layers, return to isotropy dominates. For unstable surface layers return to isotropy dominates for small filter widths, whereas for large filter widths the ground blockage effect dominates, resulting in strong anisotropy. Analyses of the terms in the budgets of the conditional mean SGS stress and SGS scalar flux, which must be correctly predicted by the SGS model in order for LES to reproduce the resolvable-scale velocity and temperature probability density functions, further reveal the complex dependence of the SGS pressure-rate-of-strain on the updrafts generated by buoyancy, downdrafts associated with the returning flow, and wall blocking effects. Under conditions of strong convective instability, the results most notably show conditional pressure redistribution from the (smaller) vertical to the (larger) horizontal velocity components during downdrafts, resulting in generation of anisotropy. The conditional mean pressure transport, meanwhile, is a significant source of energy during updrafts as a result of the near-wall pressure minima. The vertical advection also plays an important role in the transfer of SGS energy. The results in the present study, particularly for the pressure-rate-of-strain, provide important insights into the near-wall SGS dynamics. We demonstrate with a scaling-based similarity model that it is possible to predict <i>a priori</i> both return-to-isotropy and generation-of-anisotropy behaviours observed for the normal (redistributive) components of the SGS pressure-rate-of-strain. The work has important implications for modelling the SGS stress using its transport equation in the convective atmospheric boundary layer. Advisors/Committee Members: Tong, Chenning, Kaye, Nigel B, Miller, Richard S, Xuan, Xiangchun.

Subjects/Keywords: atmospheric flows; large-eddy simulation; turbulence modeling; turbulent boundary layers; Mechanical Engineering

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APA (6^th Edition):

Nguyen, K. (2015). On subgrid-scale physics in the convective atmospheric surface layer. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/1600

Chicago Manual of Style (16^th Edition):

Nguyen, Khuong. “On subgrid-scale physics in the convective atmospheric surface layer.” 2015. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/1600.

MLA Handbook (7^th Edition):

Nguyen, Khuong. “On subgrid-scale physics in the convective atmospheric surface layer.” 2015. Web. 11 Apr 2021.

Vancouver:

Nguyen K. On subgrid-scale physics in the convective atmospheric surface layer. [Internet] [Doctoral dissertation]. Clemson University; 2015. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/1600.

Council of Science Editors:

Nguyen K. On subgrid-scale physics in the convective atmospheric surface layer. [Doctoral Dissertation]. Clemson University; 2015. Available from: https://tigerprints.clemson.edu/all_dissertations/1600

10. Culberson, Austin. FEASIBILITY ANALYSIS OF STEAM VENTILATION IN SUPERCAVITATION DESIGN.

Degree: MS, Mechanical Engineering, 2015, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/2192

► The complete envelopment of a submerged object by a continuous cavity, or supercavity, results in significant reduction of the skin drag acting on the object,… (more)

▼ The complete envelopment of a submerged object by a continuous cavity, or supercavity, results in significant reduction of the skin drag acting on the object, allowing for substantial increases in the maximum speeds of underwater devices. The formation of supercavities often requires supplemental ventilation, traditionally by non-condensable gasses, as natural supercavitation occurs at relative speeds between the object and liquid medium that are infeasible for the device to reach without supercavitation itself. The aim of this research is to investigate the feasibility of vaporous ventilation in supercavitation design with the hope of reducing non-condensable ventilation requirements which are inherently limited in their supply for submerged devices. Specifically, the partial or complete replacement of non-condensable gasses with steam for ventilated supercavitation was investigated to determine the effect on cavity development and ventilation requirements. While the use of vaporous ventilation gasses was unfound throughout the extensive literature review, a theoretical analysis which drew from various ventilation scenarios of steam insertion into liquid pools or flows suggested limited potential for the sole use of steam as a ventilation gas. In addition to a theoretical evaluation, cavitator systems were designed and tested to obtain both qualitative and quantitative results. Modest increases in the cavity volume and length were seen for very specific combinations of concurrent ventilation of steam and air relative to air only ventilation. The overall advantages appear extremely limited, however, as the ventilation requirements for steam addition are roughly an order of magnitude larger compared to the required increases of non-condensable ventilation for the production of similar results. Steam alone was shown to be entirely incapable of generating continuous cavitation structures for the range of steam flowrates tested, the upper limit being over three orders of magnitude larger than the critical air ventilation flowrate needed for successful creation of a continuous attached cavity. As such, the advantages of steam ventilation in supercavitation design appear very limited at best when compared to the relative ease of ventilated supercavity development by non-condensable gasses. Advisors/Committee Members: Ochterbeck, Jay M, Tong, Chenning, Xuan, Xiangchun.

Subjects/Keywords: Cavitation; Design; Steam; Supercavitation; Ventilated; Engineering

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APA (6^th Edition):

Culberson, A. (2015). FEASIBILITY ANALYSIS OF STEAM VENTILATION IN SUPERCAVITATION DESIGN. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/2192

Chicago Manual of Style (16^th Edition):

Culberson, Austin. “FEASIBILITY ANALYSIS OF STEAM VENTILATION IN SUPERCAVITATION DESIGN.” 2015. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/2192.

MLA Handbook (7^th Edition):

Culberson, Austin. “FEASIBILITY ANALYSIS OF STEAM VENTILATION IN SUPERCAVITATION DESIGN.” 2015. Web. 11 Apr 2021.

Vancouver:

Culberson A. FEASIBILITY ANALYSIS OF STEAM VENTILATION IN SUPERCAVITATION DESIGN. [Internet] [Masters thesis]. Clemson University; 2015. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/2192.

Council of Science Editors:

Culberson A. FEASIBILITY ANALYSIS OF STEAM VENTILATION IN SUPERCAVITATION DESIGN. [Masters Thesis]. Clemson University; 2015. Available from: https://tigerprints.clemson.edu/all_theses/2192

11. Yavari, Ramin. NOVEL SIDE-VENT-CHANNEL BASED BLAST MITIGATION CONCEPT FOR LIGHT TACTICAL VEHICLES.

Degree: MS, Mechanical Engineering, 2013, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/1734

► A new concept solution for improving survivability of the light tactical military vehicles to blast-loads resulting from a shallow-buried mine detonated underneath such vehicles… (more)

▼ A new concept solution for improving survivability of the light tactical military vehicles to blast-loads resulting from a shallow-buried mine detonated underneath such vehicles is proposed and critically assessed using computational engineering methods and tools. The solution is inspired by the principle of operation of the rocket-engine nozzles, in general and the so called 'pulse detonation' rocket engines, in particular, and is an extension of the recently introduced so-called 'blast chimney' concept (essentially a vertical channel connecting the bottom and the roof and passing through the cabin of a light tactical vehicle). Relative to the blast-chimney concept, the new solution offers benefits since it does not compromise the cabin space or the ability of the vehicle occupants to scout the environment and, is not expected to, degrade the vehicle's off-road structural durability/reliability. The proposed concept utilizes properly sized and shaped side-vent channels attached to the V-shaped vehicle underbody. The utility and the blast-mitigation capacity of this concept is examined in the present work using different (i.e. coupled Eulerian/Lagrangian and coupled finite-element/discrete-particle) computational methods and tools. To maximize the blast-mitigation potential of the proposed solution, standard engineering optimization methods and tools are employed for the design of side-vent-channels. It is shown that, by proper shaping and sizing of the side-vent-channels, venting of ejected soil and supersonically-expanding gaseous detonation products can be promoted, resulting in an increase in the downward thrust on the targeted vehicle. Furthermore, it is found that optimization of the geometry and size of the side-vent-channel solution for the maximum blast-mitigation performance, requires consideration of a tradeoff between the maximum reductions in the detonation-induced total momentum transferred to, and the acceleration acquired by, the target vehicle. The results obtained farther confirmed theblast-mitigation effects of the side-vent-channels, although the extent of these effects is relatively small (3-4%). Advisors/Committee Members: Grujicic, Mica, Tong, Chenning, Ochterbeck, Jay.

Subjects/Keywords: Blast and Soil Ejecta Loading; Computational Engineering and Design-Optimization Analyses; Side Vent Channels; Mechanical Engineering

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APA (6^th Edition):

Yavari, R. (2013). NOVEL SIDE-VENT-CHANNEL BASED BLAST MITIGATION CONCEPT FOR LIGHT TACTICAL VEHICLES. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/1734

Chicago Manual of Style (16^th Edition):

Yavari, Ramin. “NOVEL SIDE-VENT-CHANNEL BASED BLAST MITIGATION CONCEPT FOR LIGHT TACTICAL VEHICLES.” 2013. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/1734.

MLA Handbook (7^th Edition):

Yavari, Ramin. “NOVEL SIDE-VENT-CHANNEL BASED BLAST MITIGATION CONCEPT FOR LIGHT TACTICAL VEHICLES.” 2013. Web. 11 Apr 2021.

Vancouver:

Yavari R. NOVEL SIDE-VENT-CHANNEL BASED BLAST MITIGATION CONCEPT FOR LIGHT TACTICAL VEHICLES. [Internet] [Masters thesis]. Clemson University; 2013. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/1734.

Council of Science Editors:

Yavari R. NOVEL SIDE-VENT-CHANNEL BASED BLAST MITIGATION CONCEPT FOR LIGHT TACTICAL VEHICLES. [Masters Thesis]. Clemson University; 2013. Available from: https://tigerprints.clemson.edu/all_theses/1734

Clemson University

12. Chen, Qinglin. INVESTIGATION OF THE EFFECTS OF SUBGRID-SCALE TURBULENCE ON RESOLVABLE-SCALE STATISTICS.

Degree: PhD, Mechanical Engineering, 2006, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/9

► The effects of the subgrid-scale (SGS) turbulence on the resolvable-scale statistics and the effects of SGS models on large-eddy simulation (LES) are studied. It is… (more)

▼ The effects of the subgrid-scale (SGS) turbulence on the resolvable-scale statistics and the effects of SGS models on large-eddy simulation (LES) are studied. It is shown that the SGS turbulence evolves the resolvable-scale joint probability density function (JPDF) through the conditional means of the SGS stress, the SGS scalar flux, and their production rate, which must be reproduced by the SGS model for LES to predict correctly the one-point resolvable-scale statistics, a primary goal of LES. This necessary condition is used as the basis for studying SGS physics and for testing SGS models. Theoretical predictions, measurements data obtained in a turbulent jet and in a convective atmospheric surface layer, and large-eddy simulation data of convective atmospheric boundary layers are combined to investigate the effects of filter size, the dependence of the SGS turbulence on the flow dynamics, and SGS models performance using new statistical a priori and a posteriori tests developed in this research. Analyses of the results show that for the inertial-range filter scales SGS predictions of the mean statistics support the premise of LES at the level of lower-order statistics, but not the higher-order statistics. For the energy-containing filter scales the conditional statistics strongly depend on the resolvable-scale velocity and temperature fluctuations, indicating the strong influence of SGS turbulence on the resolvable-scale statistics. The current SGS models have varying levels of performance in predicting different SGS components. The results suggests that efforts to improve SGS models need to ensure that all the relevant SGS fluxes related to the LES statistics are correct predicted. Given the strong dependence of the conditional statistics on the flow dynamics, it may be necessary to incorporate some aspects of the dynamics to correctly predict these conditional statistics. The statistical a posteriori test results are generally consistent with the a priori test results. Similar model strengths and deficiencies are identified in both types of tests. Therefore, analyses of the conditional statistics can serve as an important guide in studying the SGS physics, identifying model deficiencies, and developing improved SGS models. Advisors/Committee Members: Tong, Chenning.

Subjects/Keywords: turbulence; large-eddy simulation; subgrid-scale modeling; atmospheric boundary layer; statistical a priori test; statistical a posteriori test; Engineering Mechanics

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APA (6^th Edition):

Chen, Q. (2006). INVESTIGATION OF THE EFFECTS OF SUBGRID-SCALE TURBULENCE ON RESOLVABLE-SCALE STATISTICS. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/9

Chicago Manual of Style (16^th Edition):

Chen, Qinglin. “INVESTIGATION OF THE EFFECTS OF SUBGRID-SCALE TURBULENCE ON RESOLVABLE-SCALE STATISTICS.” 2006. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/9.

MLA Handbook (7^th Edition):

Chen, Qinglin. “INVESTIGATION OF THE EFFECTS OF SUBGRID-SCALE TURBULENCE ON RESOLVABLE-SCALE STATISTICS.” 2006. Web. 11 Apr 2021.

Vancouver:

Chen Q. INVESTIGATION OF THE EFFECTS OF SUBGRID-SCALE TURBULENCE ON RESOLVABLE-SCALE STATISTICS. [Internet] [Doctoral dissertation]. Clemson University; 2006. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/9.

Council of Science Editors:

Chen Q. INVESTIGATION OF THE EFFECTS OF SUBGRID-SCALE TURBULENCE ON RESOLVABLE-SCALE STATISTICS. [Doctoral Dissertation]. Clemson University; 2006. Available from: https://tigerprints.clemson.edu/all_dissertations/9

Clemson University

13. Dinger, Matthew. EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET.

Degree: MS, Mechanical Engineering, 2009, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/593

► In the present study we investigate three-stream scalar mixing in a turbulent coaxial jet. In this flow the center jet and the annulus, consisting of… (more)

▼ In the present study we investigate three-stream scalar mixing in a turbulent coaxial jet. In this flow the center jet and the annulus, consisting of acetone-doped air and ethylene respectively, are mixed with the co-flow air. A unique aspect of this study compared to previous studies of three-scalar mixing is that two of the scalars (the center jet and air) are separated from the third (annulus); therefore, this flow better approximates the mixing process in a nonpremixed turbulent reactive flow. Planar laser-indiced fluorescence and Rayleigh scattering are employed to measure the mass fractions of the acetone-doped air and ethylene, respectively. The results show that the most unique development of the three-scalar mixing occurs in the near field of the flow. The mixing process in this part of the flow are analyzed in detail using the scalar means, variances, correlation coefficient, joint probability density functions (JPDF), conditional diffusion, and conditional dissipation rate. The conditional scalar diffusion velocity streamlines in scalar space generally converge quickly to a manifold along which they continue at lower velocities. Current mixing models do not exhibit such a trend. The approach to the manifold is generally in the direction of the annulus scalar. The different magnitudes of the diffusion velocity components for the two scalars cannot be accounted for by their different dissipation time scales. The mixing processes during the approach to the manifold, therefore, cannot be modeled by using different dissipation time scales alone. While the three scalars in this flow have the same distance in scalar space, mixing between two of the scalars can occur only through the third, forcing a detour of the manifold (mixing path) in scalar space. This mixing path provides a challenging test for mixing models as most mixing models use only scalar-space variables and do not take into account the spatial (physical-space) scalar structure. The scalar JPDF and the conditional dissipation rates obtained in the present study have similarities to these of mixture fraction and temperature in turbulent flames. The present study, therefore, is an important step towards understanding and modeling multiscalar mixing in reactive flows. Advisors/Committee Members: Tong, Chenning, Figliola , Richard, Miller , Richard.

Subjects/Keywords: Diffusion; Dissipation; Mixing; Turbulence; Aerospace Engineering

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APA (6^th Edition):

Dinger, M. (2009). EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/593

Chicago Manual of Style (16^th Edition):

Dinger, Matthew. “EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET.” 2009. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/593.

MLA Handbook (7^th Edition):

Dinger, Matthew. “EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET.” 2009. Web. 11 Apr 2021.

Vancouver:

Dinger M. EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET. [Internet] [Masters thesis]. Clemson University; 2009. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/593.

Council of Science Editors:

Dinger M. EXPERIMENTAL STUDY OF THE THREE-STREAM SCALAR MIXING IN A TURBULENT COAXIAL JET. [Masters Thesis]. Clemson University; 2009. Available from: https://tigerprints.clemson.edu/all_theses/593

Clemson University

14. Foster, Justin. A priori Analysis of Subgrid Scalar Phenomena and Mass Diffusion Vectors in Turbulent Hydrogen-Oxygen Flames.

Degree: MS, Mechanical Engineering, 2009, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/571

► Direct Numerical Simulations (DNS) of high pressure, turbulent H₂/O₂ non-premixed flames employing real gas effects, detailed chemistry, multicomponent, differential, and cross diffusion are conducted. The… (more)

Subjects/Keywords: Direct Numerical Simulation; Large Eddy Simulation; Turbulent Combustion; Engineering Mechanics

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APA (6^th Edition):

Foster, J. (2009). A priori Analysis of Subgrid Scalar Phenomena and Mass Diffusion Vectors in Turbulent Hydrogen-Oxygen Flames. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/571

Chicago Manual of Style (16^th Edition):

Foster, Justin. “A priori Analysis of Subgrid Scalar Phenomena and Mass Diffusion Vectors in Turbulent Hydrogen-Oxygen Flames.” 2009. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/571.

MLA Handbook (7^th Edition):

Foster, Justin. “A priori Analysis of Subgrid Scalar Phenomena and Mass Diffusion Vectors in Turbulent Hydrogen-Oxygen Flames.” 2009. Web. 11 Apr 2021.

Vancouver:

Foster J. A priori Analysis of Subgrid Scalar Phenomena and Mass Diffusion Vectors in Turbulent Hydrogen-Oxygen Flames. [Internet] [Masters thesis]. Clemson University; 2009. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/571.

Council of Science Editors:

Foster J. A priori Analysis of Subgrid Scalar Phenomena and Mass Diffusion Vectors in Turbulent Hydrogen-Oxygen Flames. [Masters Thesis]. Clemson University; 2009. Available from: https://tigerprints.clemson.edu/all_theses/571

Clemson University

15. Race, Nathan. PROPERTY MEASUREMENTS AND EVALUATION OF HEAT LEAK.

Degree: MS, Mechanical Engineering, 2007, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/267

► Heat transport in capillary wick structures is an important parameter in loop heat pipe (LHP) design. The purpose of this study was to investigate the… (more)

Subjects/Keywords: Loop; Heat; Pipe; Leak; evaporation; transfer; Engineering Mechanics

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APA (6^th Edition):

Race, N. (2007). PROPERTY MEASUREMENTS AND EVALUATION OF HEAT LEAK. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/267

Chicago Manual of Style (16^th Edition):

Race, Nathan. “PROPERTY MEASUREMENTS AND EVALUATION OF HEAT LEAK.” 2007. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/267.

MLA Handbook (7^th Edition):

Race, Nathan. “PROPERTY MEASUREMENTS AND EVALUATION OF HEAT LEAK.” 2007. Web. 11 Apr 2021.

Vancouver:

Race N. PROPERTY MEASUREMENTS AND EVALUATION OF HEAT LEAK. [Internet] [Masters thesis]. Clemson University; 2007. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/267.

Council of Science Editors:

Race N. PROPERTY MEASUREMENTS AND EVALUATION OF HEAT LEAK. [Masters Thesis]. Clemson University; 2007. Available from: https://tigerprints.clemson.edu/all_theses/267

Clemson University

16. Vasudevan, Soundararaghavan. Thermal diffusion coefficient modeling for high pressure combustion simulations.

Degree: MS, Mechanical Engineering, 2007, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/278

► The effects of Soret and Dufour diffusion on the behavior of high pressure laminar diffusion flames relevant to modern combustion devices are investigated. A novel… (more)

Subjects/Keywords: Engineering Mechanics

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APA (6^th Edition):

Vasudevan, S. (2007). Thermal diffusion coefficient modeling for high pressure combustion simulations. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/278

Chicago Manual of Style (16^th Edition):

Vasudevan, Soundararaghavan. “Thermal diffusion coefficient modeling for high pressure combustion simulations.” 2007. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/278.

MLA Handbook (7^th Edition):

Vasudevan, Soundararaghavan. “Thermal diffusion coefficient modeling for high pressure combustion simulations.” 2007. Web. 11 Apr 2021.

Vancouver:

Vasudevan S. Thermal diffusion coefficient modeling for high pressure combustion simulations. [Internet] [Masters thesis]. Clemson University; 2007. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/278.

Council of Science Editors:

Vasudevan S. Thermal diffusion coefficient modeling for high pressure combustion simulations. [Masters Thesis]. Clemson University; 2007. Available from: https://tigerprints.clemson.edu/all_theses/278

Clemson University

17. Cai, Jian. Investigation of subgrid-scale mixing and turbulence-chemistry interaction in turbulent partially premixed flames using experimental data.

Degree: PhD, Mechanical Engineering, 2010, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/597

► The filtered mass density function (FMDF) of mixture fraction, temperature and species used in large eddy simulation (LES) of turbulent combustion is studied experimentally using… (more)

▼ The filtered mass density function (FMDF) of mixture fraction, temperature and species used in large eddy simulation (LES) of turbulent combustion is studied experimentally using line images obtained in turbulent partially premixed methane flames (Sandia flames D and E). Cross-stream filtering is employed to obtain the FMDF and other filtered variables. The mean of the FMDF conditional on the subgrid-scale (SGS) scalar variance at a given location are found to vary from unimodal to bimodal, corresponding to quasi-equilibrium distributed reaction zones and laminar flamelets (including extinguished flamelets), respectively. The conditionally filtered mixture fraction dissipation for small SGS variances has a relatively weak dependence on the mixture fraction, and is not sensitive to temperature for extinguished samples. For large SGS variance the large dissipation is concentrated in the cliffs and increases with decreasing temperature. The conditionally filtered temperature dissipation for small SGS variances is the highest for intermediate temperature. For large SGS variance the dependence is more complex and the pilot gas appears to be playing an important role. The conditionally filtered scalar and temperature diffusion for small SGS variance have a simple structure. For large SGS variance the diffusion structure is much more complex, with the pilot and local extinction also playing important roles. The results show that it is important that mixing models for filtered density function methods be able to account for the different SGS mixture fraction and temperature structures for small and large SGS variance. The different SGS mixture fraction structures for small and large SGS variances, as reflected by the unimodal and bimodal FMDF, have a strong impact on the small-scale mixing and turbulence-chemistry interaction, as reflected by the results for the conditionally filtered dissipation rates and diffusion. The results have implications for understanding and modeling multiple reactive scalar SGS mixing. Scalar dissipation rate is an important quantity in turbulent mixing and combustion. Its measurement depends on two opposite trends, noise and resolution effects, making their separation and accurate corrections difficult. A major task in dissipation rate correction, therefore, is to isolate each effect. A conditional sampling-based method for correcting noise and resolution effects for scalar dissipation rate measurements is developed. The conditional-sampling method uses instantaneous local scalar mean and variance as conditioning variables, and is based in part on Kolmogorov's refined similarity hypotheses. It ensures selection of instantaneous fully resolved local scalar fields, which are analyzed to determine the measurement noise. Noise correction is applied to potentially under-resolved local scalar fields, also selected using the conditional-sampling procedure, effectively separating the effects of noise from those of resolution. The error function is used as a model for the potentially… Advisors/Committee Members: Tong, Chenning, Ma , Lin, Miller , Richard S, Park , Chanseok.

Subjects/Keywords: measurement noise; turbulence-chemistry interaction; turbulent combustion; turbulent mixing; Engineering Mechanics

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APA (6^th Edition):

Cai, J. (2010). Investigation of subgrid-scale mixing and turbulence-chemistry interaction in turbulent partially premixed flames using experimental data. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/597

Chicago Manual of Style (16^th Edition):

Cai, Jian. “Investigation of subgrid-scale mixing and turbulence-chemistry interaction in turbulent partially premixed flames using experimental data.” 2010. Doctoral Dissertation, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_dissertations/597.

MLA Handbook (7^th Edition):

Cai, Jian. “Investigation of subgrid-scale mixing and turbulence-chemistry interaction in turbulent partially premixed flames using experimental data.” 2010. Web. 11 Apr 2021.

Vancouver:

Cai J. Investigation of subgrid-scale mixing and turbulence-chemistry interaction in turbulent partially premixed flames using experimental data. [Internet] [Doctoral dissertation]. Clemson University; 2010. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_dissertations/597.

Council of Science Editors:

Cai J. Investigation of subgrid-scale mixing and turbulence-chemistry interaction in turbulent partially premixed flames using experimental data. [Doctoral Dissertation]. Clemson University; 2010. Available from: https://tigerprints.clemson.edu/all_dissertations/597

Clemson University

18. Lee, Richard. The Effect of a Surfactant Monolayer on Gas Exchange Across an Air-Water Interface during Mixed Convection.

Degree: MS, Mechanical Engineering, 2009, Clemson University

URL: https://tigerprints.clemson.edu/all_theses/678

► A set of laboratory experiments are presented that reveal the effect of a surfactant monolayer on the transport of oxygen across an air-water interface during… (more)

▼ A set of laboratory experiments are presented that reveal the effect of a surfactant monolayer on the transport of oxygen across an air-water interface during mixed convection conditions. The experiments were conducted in a wind/water tunnel with water tanks of differing depth. Forced convection was imposed via the air flow, while natural convection was imposed by heating the water bulk above the air temperature. For the range of wind speeds being considered, mixed convection conditions resulted. Experiments were also conducted with only forced convection present. The data acquired during these experiments were used to develop a parameterization between the Sherwood number for oxygen transport (Sh) and the Reynolds (Re), Rayleigh (Ra), and Schmidt (Sc) numbers. This parameterization was obtained for the case of a clean water surface and for a water surface covered with one of two surfactant monolayers, controlled (oleyl alcohol) and uncontrolled (indigenous). The data reveal that, at a given Ra, the presence of a surfactant monolayer reduces the value of Sh by approximately one order of magnitude. This reduction is caused by the reduction of subsurface turbulence caused by the presence of the surfactant monolayer. The data also show that Sh was relatively insensitive to Re and Sc when a surfactant monolayer was present, which is verified by the forced convection only results. However, Sh was dependent on Ra, Re, and Sc for the clean water surface condition. For the two surfactant conditions, no change in behavior of the gas exchange was noticed. The elasticity of the air-water interface which results from the presence of a surfactant is used to explain the difference between clean surface and surfactant-covered results. The elasticity imparted by a surfactant monolayer is also used to explain the similarity of the results for the two surfactants. For both the clean and surfactant cases, Sh increases with Ra. Advisors/Committee Members: Saylor, John R, Beasley , Donald E, Tong , Chenning.

Subjects/Keywords: Engineering Mechanics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Lee, R. (2009). The Effect of a Surfactant Monolayer on Gas Exchange Across an Air-Water Interface during Mixed Convection. (Masters Thesis). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_theses/678

Chicago Manual of Style (16^th Edition):

Lee, Richard. “The Effect of a Surfactant Monolayer on Gas Exchange Across an Air-Water Interface during Mixed Convection.” 2009. Masters Thesis, Clemson University. Accessed April 11, 2021. https://tigerprints.clemson.edu/all_theses/678.

MLA Handbook (7^th Edition):

Lee, Richard. “The Effect of a Surfactant Monolayer on Gas Exchange Across an Air-Water Interface during Mixed Convection.” 2009. Web. 11 Apr 2021.

Vancouver:

Lee R. The Effect of a Surfactant Monolayer on Gas Exchange Across an Air-Water Interface during Mixed Convection. [Internet] [Masters thesis]. Clemson University; 2009. [cited 2021 Apr 11]. Available from: https://tigerprints.clemson.edu/all_theses/678.

Council of Science Editors:

Lee R. The Effect of a Surfactant Monolayer on Gas Exchange Across an Air-Water Interface during Mixed Convection. [Masters Thesis]. Clemson University; 2009. Available from: https://tigerprints.clemson.edu/all_theses/678

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