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Virginia Tech
1.
Higgins, Erik Tracy.
Multi-Scale Localized Perturbation Method for Geophysical Fluid Flows.
Degree: MS, Aerospace Engineering, 2020, Virginia Tech
URL: http://hdl.handle.net/10919/99889 
► Natural flows, such as those in our oceans and atmosphere, are seen everywhere and affect human life and structures to an amazing degree. Study of…
(more)
▼ Natural flows, such as those in our oceans and atmosphere, are seen everywhere and affect human life and structures to an amazing degree. Study of these complex flows requires special care be taken to ensure that mathematical equations correctly approximate them and that computers are programmed to correctly solve these equations. This is no different for researchers and engineers interested in studying how man-made flows, such as one generated by the wake of a plane, wind turbine, cruise ship, or sewage outflow pipe, interact with natural flows found around the world. These interactions may yield complex phenomena that may not otherwise be observed in the natural flows alone. The natural and artificial flows may also mix together, rendering it difficult to study just one of them. The multi-scale localized perturbation method is devised to aid in the simulation and study of the interactions between these natural and man-made flows. Well-known equations of fluid dynamics are modified so that the natural and man-made flows are separated and tracked independently, which gives researchers a clear view of the current state of a region of air or water all while retaining most, if not all, of the complex physics which may be of interest.
Once the multi-scale localized perturbation method is derived, its mathematical equations are then translated into code for OpenFOAM, an open-source software toolkit designed to simulate fluid flows. This code is then tested by running simulations to provide a sanity check and verify that the new form of the equations of fluid dynamics have been programmed correctly, then another, more complicated simulation is run to showcase the benefits of the multi-scale localized perturbation method. This simulation shows some of the complex fluid phenomena that may be seen in nature, yet through the multi-scale localized perturbation method, it is easy to view where the man-made flows end and where the natural flows begin. The complex interactions between the natural flow and the artificial flow are retained in spite of separating the flow into two parts, and setting up the simulation is simplified by this separation. Potential uses of the multi-scale localized perturbation method include multi-scale simulations, where researchers simulate natural flow over a large area of land or ocean, then use this simulation data for a second, small-scale simulation which covers an area within the large-scale simulation. An example of this would be simulating wind currents across a continent to find a potential location for a wind turbine farm, then zooming in on that location and finding the optimal spacing for wind turbines at this location while using the large-scale simulation data to provide realistic wind conditions at many different heights above the ground. Overall, the multi-scale localized perturbation method has the potential to be a powerful tool for researchers whose interest is flows in the ocean and atmosphere, and how these natural flows interact with flows created by artificial means.
Advisors/Committee Members: Paterson, Eric G. (committeechair), Pitt, Jonathan (committeechair), Xiao, Heng (committee member).
Subjects/Keywords: computational fluid dynamics; non-linear interaction; multi-scale modeling; OpenFOAM; ocean physics
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APA (6th Edition):
Higgins, E. T. (2020). Multi-Scale Localized Perturbation Method for Geophysical Fluid Flows. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/99889
Chicago Manual of Style (16th Edition):
Higgins, Erik Tracy. “Multi-Scale Localized Perturbation Method for Geophysical Fluid Flows.” 2020. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/99889.
MLA Handbook (7th Edition):
Higgins, Erik Tracy. “Multi-Scale Localized Perturbation Method for Geophysical Fluid Flows.” 2020. Web. 07 Mar 2021.
Vancouver:
Higgins ET. Multi-Scale Localized Perturbation Method for Geophysical Fluid Flows. [Internet] [Masters thesis]. Virginia Tech; 2020. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/99889.
Council of Science Editors:
Higgins ET. Multi-Scale Localized Perturbation Method for Geophysical Fluid Flows. [Masters Thesis]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/99889
2.
Battista, Thomas Andrew.
Lagrangian Mechanics Modeling of Free Surface-Affected Marine Craft.
Degree: PhD, Aerospace Engineering, 2018, Virginia Tech
URL: http://hdl.handle.net/10919/82928
► Although ships have been used for thousands of years, modeling the dynamics of marine craft has historically been restricted by the complex nature of the…
(more)
▼ Although ships have been used for thousands of years, modeling the dynamics of marine craft has historically been restricted by the complex nature of the hydrodynamics. The principal challenge is that the vehicle motion is coupled to the ambient fluid motion, effectively requiring one to solve an infinite dimensional set of equations to predict the hydrodynamic forces and moments acting on a marine vehicle. Additional challenges arise in parametric modeling, where one approximates the fluid behavior using reduced-order ordinary differential equations. Parametric models are typically required for model-based state estimation and feedback control design, while also supporting other applications including vehicle design and submarine operator training.
In this dissertation, Lagrangian mechanics is used to derive nonlinear, parametric motion models for marine craft operating in the presence of a free surface. In Lagrangian mechanics, one constructs the equations of motion for a dynamic system using a system Lagrangian, a scalar energy-like function canonically defined as the system kinetic energy minus the system potential energies. The Lagrangian functions are identified under ideal flow assumptions and are used to derive two sets of equations. The first set of equations neglects hydrodynamic forces due to exogenous fluid motions and may be interpreted as a nonlinear calm water maneuvering model. The second set of equations incorporates effects due to exogenous fluid motion, and may be interpreted as a nonlinear, unified maneuvering and seakeeping model. Having identified the state- and time-dependent model parameters, one may use these models to rapidly simulate surface-affected marine craft maneuvers, enabling model-based control design and state estimation algorithms.
Advisors/Committee Members: Woolsey, Craig A. (committeechair), Valentinis, Francis (committeechair), Brizzolara, Stefano (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: Lagrangian Mechanics; Potential Flow Hydrodynamics; Fluid-Body Interactions
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APA (6th Edition):
Battista, T. A. (2018). Lagrangian Mechanics Modeling of Free Surface-Affected Marine Craft. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/82928
Chicago Manual of Style (16th Edition):
Battista, Thomas Andrew. “Lagrangian Mechanics Modeling of Free Surface-Affected Marine Craft.” 2018. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/82928.
MLA Handbook (7th Edition):
Battista, Thomas Andrew. “Lagrangian Mechanics Modeling of Free Surface-Affected Marine Craft.” 2018. Web. 07 Mar 2021.
Vancouver:
Battista TA. Lagrangian Mechanics Modeling of Free Surface-Affected Marine Craft. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/82928.
Council of Science Editors:
Battista TA. Lagrangian Mechanics Modeling of Free Surface-Affected Marine Craft. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/82928
Virginia Tech
3.
Martin, Christian Tyler.
Turbulent Simulations of a Buoyant Jet-in-Crossflow.
Degree: MS, Aerospace Engineering, 2020, Virginia Tech
URL: http://hdl.handle.net/10919/96335
► A lack of complex analysis for a heated jet in a non-uniform crossflow has motivated the studies presented. A computational approach for the fluid dynamics…
(more)
▼ A lack of complex analysis for a heated jet in a non-uniform crossflow has
motivated the studies presented. A computational approach for the fluid dynamics
governing equations under specific assumptions is implemented. Additional equations
are solved for temperature and salinity in conjunction with a linear equation of state to
obtain the density field. Comparing simulations to experimental data
of a point heat source in a non-uniform, fluid tank provides general agreement between
the aforementioned computational model and the physics studied. Studying the literature
yields no unified agreement on the selection of turbulence treatment for the jet-in-crossflow
problem. For this reason, a comparison is presented for two various techniques with
differing complexity. The mathematical differences as well as the implications
each model are outlined, specifically pertaining to a heated jet in a non-uniform
crossflow. The simpler
model provides a general over prediction when compared to the more complex model.
Studies involving the removal of the heat from inside the jet as well as varying the
environmental forcing have largely determined that these affects do not alter the
flow field near the jet's origin point in any significant way. Changing the jet's velocity
has provided information on the variability
of the forcing on the plate the jet exits from, as well as in the energy released into the
environment far downstream of the jet's exit. The ratios presented show that any
deviation from a notional value provides an increase in the overall forces seen by the
plate. It was also found that the change in the released energies is proportional to the
deviation from the notional jet velocity.
Advisors/Committee Members: Paterson, Eric G. (committeechair), Lowe, Kevin T. (committee member), Pitt, Jonathan (committee member).
Subjects/Keywords: HRLES; JICF; buoyant; crossflow; DES; CFD; OpenFOAM; near-field
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APA (6th Edition):
Martin, C. T. (2020). Turbulent Simulations of a Buoyant Jet-in-Crossflow. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/96335
Chicago Manual of Style (16th Edition):
Martin, Christian Tyler. “Turbulent Simulations of a Buoyant Jet-in-Crossflow.” 2020. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/96335.
MLA Handbook (7th Edition):
Martin, Christian Tyler. “Turbulent Simulations of a Buoyant Jet-in-Crossflow.” 2020. Web. 07 Mar 2021.
Vancouver:
Martin CT. Turbulent Simulations of a Buoyant Jet-in-Crossflow. [Internet] [Masters thesis]. Virginia Tech; 2020. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/96335.
Council of Science Editors:
Martin CT. Turbulent Simulations of a Buoyant Jet-in-Crossflow. [Masters Thesis]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/96335
Virginia Tech
4.
McCall, Andrew James.
Multi-level Parallelism with MPI and OpenACC for CFD Applications.
Degree: MS, Aerospace Engineering, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/78203
► High-level parallel programming approaches, such as OpenACC, have recently become popular in complex fluid dynamics research since they are cross-platform and easy to implement. OpenACC…
(more)
▼ High-level parallel programming approaches, such as OpenACC, have recently become popular in complex fluid dynamics research since they are cross-platform and easy to implement. OpenACC is a directive-based programming model that, unlike low-level programming models, abstracts the details of implementation on the GPU. Although OpenACC generally limits the performance of the GPU, this model significantly reduces the work required to port an existing code to any accelerator platform, including GPUs. The purpose of this research is twofold: to investigate the effectiveness of OpenACC in developing a portable and maintainable GPU-accelerated code, and to determine the capability of OpenACC to accelerate large, complex programs on the GPU. In both of these studies, the OpenACC implementation is optimized and extended to a multi-GPU implementation while maintaining a unified code base. OpenACC is shown as a viable option for GPU computing with CFD problems.
In the first study, a CFD code that solves incompressible cavity flows is accelerated using OpenACC. Overlapping communication with computation improves performance for the multi-GPU implementation by up to 21%, achieving up to 400 times faster performance than a single CPU and 99% weak scalability efficiency with 32 GPUs.
The second study ports the execution of a more complex CFD research code to the GPU using OpenACC. Challenges using OpenACC with modern Fortran are discussed. Three test cases are used to evaluate performance and scalability. The multi-GPU performance using 27 GPUs is up to 100 times faster than a single CPU and maintains a weak scalability efficiency of 95%.
Advisors/Committee Members: Roy, Christopher John (committeechair), Paterson, Eric G. (committee member), De Sturler, Eric (committee member).
Subjects/Keywords: Graphics processing unit; Directive-based programming; OpenACC; Lid-driven cavity; Multi-GPU; Parallel computing
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APA (6th Edition):
McCall, A. J. (2017). Multi-level Parallelism with MPI and OpenACC for CFD Applications. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/78203
Chicago Manual of Style (16th Edition):
McCall, Andrew James. “Multi-level Parallelism with MPI and OpenACC for CFD Applications.” 2017. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/78203.
MLA Handbook (7th Edition):
McCall, Andrew James. “Multi-level Parallelism with MPI and OpenACC for CFD Applications.” 2017. Web. 07 Mar 2021.
Vancouver:
McCall AJ. Multi-level Parallelism with MPI and OpenACC for CFD Applications. [Internet] [Masters thesis]. Virginia Tech; 2017. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/78203.
Council of Science Editors:
McCall AJ. Multi-level Parallelism with MPI and OpenACC for CFD Applications. [Masters Thesis]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/78203
Virginia Tech
5.
Jung, Se Yong.
Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves.
Degree: PhD, Aerospace Engineering, 2020, Virginia Tech
URL: http://hdl.handle.net/10919/97332
► A unified maneuvering and seakeeping model for a submerged vessel maneuvering near waves describes mathematically the relationship between input values to the dynamical system, such…
(more)
▼ A unified maneuvering and seakeeping model for a submerged vessel maneuvering near waves describes mathematically the relationship between input values to the dynamical system, such as thrust from the propulsors, and output values from the system, such as the position and orientation of the vessel. This unified model has a wide range of applications, ranging from vessel hull form optimization in the early design phase to motion controller tuning after the vessel has been constructed. In order for a unified model to make accurate predictions, for instance, for a submerged vessel making a rapid turn near large waves, nonlinear effects have to be included in the model formulation. To that end, a nonlinear motion model for a marine craft affected by a free surface has been developed using Lagrangian mechanics. This dissertation describes an approach for determining the parameters of the nonlinear motion model using a potential flow panel code, which is originally designed to determine flow velocity of the fluid and pressure distribution over marine vessels. The nonlinear motion model is reformulated and the software implementation is modified to support parameter computations. In addition, the methods are numerically validated by comparing computations using the model against solutions output by the panel code. Compared to traditional parameter estimation approaches, the proposed methods allow for a more accurate and efficient determination of parameters of the nonlinear potential flow model for a submerged vessel operating near waves. The resulting Lagrangian nonlinear maneuvering and seakeeping (LNMS) model with determined parameters is able to capture critical nonlinear effects and has applications such as nonlinear control design, rapid design optimization and training simulator development.
Advisors/Committee Members: Woolsey, Craig A. (committeechair), Brizzolara, Stefano (committeechair), Valentinis, Francis (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: submerged vessel dynamics; hydrodynamic force; Lagrangian mechanics; free surface; maneuvering and seakeeping
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APA (6th Edition):
Jung, S. Y. (2020). Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/97332
Chicago Manual of Style (16th Edition):
Jung, Se Yong. “Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves.” 2020. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/97332.
MLA Handbook (7th Edition):
Jung, Se Yong. “Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves.” 2020. Web. 07 Mar 2021.
Vancouver:
Jung SY. Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves. [Internet] [Doctoral dissertation]. Virginia Tech; 2020. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/97332.
Council of Science Editors:
Jung SY. Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves. [Doctoral Dissertation]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/97332
Virginia Tech
6.
Afonja, Adetoso J.
Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device.
Degree: MS, Ocean Engineering, 2020, Virginia Tech
URL: http://hdl.handle.net/10919/98782
► This study present results of an investigation into a new type of wave energy converter which can be deployed in ocean and by its pitch…
(more)
▼ This study present results of an investigation into a new type of wave energy converter which can be deployed in ocean and by its pitch response motion, it can harvest wave energy and convert it to electrical energy. This device consist of a floater, a U-tank (resonant U-tank) with sloshing water free to oscillate in response to the floater motion and a pneumatic turbine which produces power as air is forced to travel across it. The pneumatic turbine is used as the power take-off (PTO) device. A medium fidelity approach was taken to carry out this study by applying Lloyd’s model which describes the motion of the sloshing water in a resonant U-tank. Computational fluid dynamics (CFD) studies were carried out to calibrate the hydrodynamic parameters of the resonant U-tank as described by Lloyd and it was discovered that these parameters are frequency dependent, therefore Lloyd’s model was modelled to be frequency dependent. The mathematical formulation coupling the thermodynamic evolution of air in the resonant U-tank chamber, modified Lloyd’s sloshing water equation, floater dynamics and PTO were presented for the integrated system. These set of thermo-hydrodynamic equations were solved with a numerical model developed using MATLAB/Simulink WEC-Sim Libraries in time domain in other to capture the non-linearity arising from the coupled dynamics. To assess the annual energy productivity of the device, wave statistical data from two resource sites, Western Hawaii and Eel River were selected and used to carrying out computations on different iterations of the device by varying the tank’s main dimensions. This results were promising with the most performing device iteration yielding mean annual energy production of 579 MWh for Western Hawaii.
Advisors/Committee Members: Brizzolara, Stefano (committeechair), Paterson, Eric G. (committee member), Woolsey, Craig A. (committee member).
Subjects/Keywords: Wave Energy Converter (WEC); Pitch Resonance Tuning Tanks; Ocean Energy Technology; Non-linear Motion in Waves; Renewable Energy; Pitch Resonant Point Absorber
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APA (6th Edition):
Afonja, A. J. (2020). Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/98782
Chicago Manual of Style (16th Edition):
Afonja, Adetoso J. “Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device.” 2020. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/98782.
MLA Handbook (7th Edition):
Afonja, Adetoso J. “Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device.” 2020. Web. 07 Mar 2021.
Vancouver:
Afonja AJ. Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device. [Internet] [Masters thesis]. Virginia Tech; 2020. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/98782.
Council of Science Editors:
Afonja AJ. Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device. [Masters Thesis]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/98782
Virginia Tech
7.
Li, Jiahui.
Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form.
Degree: MS, Ocean Engineering, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/89904
► The paper presents the first series of results obtained in an ongoing validation and verification study of inter-dynamic OpenFOAM solver framework on a new set…
(more)
▼ The paper presents the first series of results obtained in an ongoing validation and verification study of inter-dynamic OpenFOAM solver framework on a new set of high quality experimental tests performed on a large (2.4m long) generic planing hull model (GPPH) with high deadrise (18deg), from the pre-planning (Fn∇=2.6) to fully planing (Fn∇=5.7) regimes. This test case is a good benchmark for the free surface capturing model implemented in OpenFOAM which is based on a rather simple transport equation for an additional scalar field that defines the fraction of water in each cell of the computational mesh. This model, in spite of its simplicity, seems capable of reproducing complex violent free surface flows such as that observed in planing hulls, that includes jet spray forming on the bottom and detaching from the chine of the planing hull and overturning waves off the wet chine region, with some nuances. The dependence of the flow solution on the mesh quality is presented and discussed. Practical indication of the level of uncertainty of CFD models for the prediction of the calm water hydrodynamics of the GPPH is given at the highest simulated speed using both fixed and free attitude simulation solutions. Predictions are then extended to the whole speed range, including resistance components, dynamic trim, heave, wetted chine length, and wetted keel length.The effect due to algorithms is also discussed by modifying the settings in wall functions and solvers for the improvements of future simulation.
Advisors/Committee Members: Brizzolara, Stefano (committeechair), Brown, Alan J. (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: Planing Hull; GPPH; OpenFOAM; URANS
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APA (6th Edition):
Li, J. (2019). Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/89904
Chicago Manual of Style (16th Edition):
Li, Jiahui. “Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form.” 2019. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/89904.
MLA Handbook (7th Edition):
Li, Jiahui. “Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form.” 2019. Web. 07 Mar 2021.
Vancouver:
Li J. Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form. [Internet] [Masters thesis]. Virginia Tech; 2019. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/89904.
Council of Science Editors:
Li J. Verification and Validation Study of OpenFOAM on the Generic Prismatic Planing Hull Form. [Masters Thesis]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/89904
Virginia Tech
8.
Clark, Ian Andrew.
A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise.
Degree: MS, Aerospace Engineering, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/51178
► The wings of most species of owl have been shown to possess three unique physical attributes which allow them to hunt in effective silence: a…
(more)
▼ The wings of most species of owl have been shown to possess three unique physical attributes which allow them to hunt in effective silence: a comb of evenly-spaced bristles along the wing leading-edge; a compliant and porous fringe of feathers at the trailing-edge; and a velvety down material distributed over the upper wing surface. This investigation focuses on the last of the mechanisms as a means to reduce noise from flow over surface roughness. A microscopic study of several owl feathers revealed the structure of the velvety down to be very similar to that of a forest or a field of crops. Analogous surface treatments (suspended canopies) were designed which simulated the most essential geometric features of the velvety down material.
The
Virginia Tech Anechoic Wall-Jet Facility was used to perform far-field noise and surface pressure fluctuation measurements in the presence of various combinations of rough surfaces and suspended canopies. All canopies were demonstrated to have a strong influence on the surface pressure spectra, and attenuations of up to 30 dB were observed. In addition, all canopies were shown to have some positive effects on far-field noise, and optimized canopies yielded far-field noise reductions of up to 8 dB across all frequencies at which roughness noise was observed. This development represents a new passive method for roughness noise control with possibility for future optimization and application to engineering structures.
Advisors/Committee Members: Devenport, William J. (committeechair), Alexander, William Nathan (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: Roughness Noise; Bio-Inspired; Noise Reduction; Noise Control; Canopies
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APA (6th Edition):
Clark, I. A. (2015). A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51178
Chicago Manual of Style (16th Edition):
Clark, Ian Andrew. “A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise.” 2015. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/51178.
MLA Handbook (7th Edition):
Clark, Ian Andrew. “A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise.” 2015. Web. 07 Mar 2021.
Vancouver:
Clark IA. A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise. [Internet] [Masters thesis]. Virginia Tech; 2015. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/51178.
Council of Science Editors:
Clark IA. A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise. [Masters Thesis]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51178
9.
Bay, Raymond James.
Improved Design Method for Cambered Stepped Hulls with High Deadrise.
Degree: MS, Ocean Engineering, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/90298
► Eugene Clement developed a new design method to improve the performance of ultra-fast planing crafts. A planing craft uses the force generated from the flow…
(more)
▼ Eugene Clement developed a new design method to improve the performance of ultra-fast planing crafts. A planing craft uses the force generated from the flow of water over the bottom to lift the vessel without the use of the static buoyancy force that classic boat designs rely on. Clement wanted to improve the performance of the planing vessel by reducing the total drag force caused by the flow of water on the bottom of the vessel. ClementâĂŹs design method involves reducing the wetted surface area which reduces drag. Reducing the wetted surface area would normally cause the lifting force on the vessel to reduce, but with the addition of curvature in the smaller wetted surface area, the lifting force would remain the same. ClementâĂŹs new design method requires multiple iterations to obtain an optimal design. The method limits the angle of the vessels bottom relative to horizontal to under 15 degree. The goal of this thesis is to create a new design method for planing vessels with bottoms that have an incline of 15 degrees or more relative to horizontal. The design method is created using Computational Fluid Dynamics (CFD) solver to model the planing surface moving through water. The CFD solver is validated with experimental test performed at the United States Naval Academy. The improved design method uses equations that can predict the forces and other design characteristics based on the desired vessel weight and seakeeping requirements.
Advisors/Committee Members: Brizzolara, Stefano (committeechair), Paterson, Eric G. (committee member), Brown, Alan J. (committee member).
Subjects/Keywords: CFD; Planing Surface; Cambered Step Hull
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APA (6th Edition):
Bay, R. J. (2019). Improved Design Method for Cambered Stepped Hulls with High Deadrise. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/90298
Chicago Manual of Style (16th Edition):
Bay, Raymond James. “Improved Design Method for Cambered Stepped Hulls with High Deadrise.” 2019. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/90298.
MLA Handbook (7th Edition):
Bay, Raymond James. “Improved Design Method for Cambered Stepped Hulls with High Deadrise.” 2019. Web. 07 Mar 2021.
Vancouver:
Bay RJ. Improved Design Method for Cambered Stepped Hulls with High Deadrise. [Internet] [Masters thesis]. Virginia Tech; 2019. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/90298.
Council of Science Editors:
Bay RJ. Improved Design Method for Cambered Stepped Hulls with High Deadrise. [Masters Thesis]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/90298
Virginia Tech
10.
Sun, Rui.
Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights.
Degree: PhD, Aerospace Engineering, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/78260
► Sediment transport is ubiquitous in aquatic environments, and the study of sediment transport is important for both engineering and environmental reasons. However, the understanding and…
(more)
▼ Sediment transport is ubiquitous in aquatic environments, and the study of sediment transport is important for both engineering and environmental reasons. However, the understanding and prediction of sediment transport are hindered by its complex dynamics and regimes. In this dissertation, the open-source solver SediFoam is developed for high-fidelity particle-resolving simulations of various sediment transport problems based on open-source solvers OpenFOAM and LAMMPS. OpenFOAM is a CFD toolbox that can perform three-dimensional flow simulations on unstructured mesh; LAMMPS is a massively parallel DEM solver for molecular dynamics. To enable the particle-resolving simulation of sediment transport on an arbitrary mesh, a diffusion-based algorithm is used in SediFoam to obtain the averaged Eulerian fields from discrete particle data. The parallel interface is also implemented for the communication of the two open-source solvers. Extensive numerical simulations are performed to validate the capability of SediFoam in the modeling of sediment transport problems. The predictions of various sediment transport regimes, including `flat bed in motion', `small dune' and `vortex dune', are in good agreement of with the experimental results and those obtained by using interface resolved simulations. The capability of the solver in the simulation of sediment transport in the oscillatory boundary layer is also demonstrated. Moreover, this well-validated high-fidelity simulation tool has been used to probe the physics of particle dynamics in self-generated bedforms in various hydraulic conditions. The results obtained by using SediFoam not only bridge the gaps in the experimental results but also help improve the engineering practice in the understanding of sediment transport. By using the particle-resolving simulation results and the insights generated therein, the closure terms in the two-fluid models or hydro-morphodynamic models can be improved, which can contribute to the numerical modeling of sediment transport in engineering scales.
Advisors/Committee Members: Xiao, Heng (committeechair), Liu, Yang (committee member), Wang, Kevin Guanyuan (committee member), Irish, Jennifer L. (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: Sediment Transport; CFD – DEM; Particle-Resolving Simulations; Multiphase Flow; Dune Migration
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APA (6th Edition):
Sun, R. (2017). Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/78260
Chicago Manual of Style (16th Edition):
Sun, Rui. “Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights.” 2017. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/78260.
MLA Handbook (7th Edition):
Sun, Rui. “Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights.” 2017. Web. 07 Mar 2021.
Vancouver:
Sun R. Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights. [Internet] [Doctoral dissertation]. Virginia Tech; 2017. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/78260.
Council of Science Editors:
Sun R. Particle-Resolving Simulations of Dune Migration: Novel Algorithms and Physical Insights. [Doctoral Dissertation]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/78260
11.
Webster, John Ackroyd III.
Design and Analysis of Low Reynolds Number Marine Propellers with Computational Fluid Dynamics (CFD) Transition Modeling.
Degree: PhD, Aerospace Engineering, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/93038
► Small-scale marine propellers exhibit transition from laminar to turbulent flow in the region near the surface of the blades. Regions of laminar and turbulent flow…
(more)
▼ Small-scale marine propellers exhibit transition from laminar to turbulent flow in the region near the surface of the blades. Regions of laminar and turbulent flow on the blade surface contribute differently to the overall thrust and torque on the propeller. Prediction of flow transition in the design process for small-scale marine propellers can improve the accuracy of the thrust and torque prediction compared to modeling the flow as purely laminar or turbulent. Propeller thrust and torque can be modeled using computational fluid dynamics (CFD) simulations, where transition modeling is accomplished by solving a transport equation for the intermittency γ, which represents the percentage of time the flow in a given location is turbulent. In this work, a transition model is coupled to a high-fidelity full Reynolds stress turbulence model, which solves 6 transport equations to solve for each component of the Reynolds stress tensor. The Reynolds stress tensor represents the turbulent velocity fluctuations in the governing equations solved in the CFD simulation. This coupled transition and turbulence model is then validated using experimental results of flows with a number of different transition mechanisms. The coupled model is then tested with a series of model-scale propellers, with results of the CFD simulations compared to the experimental results. A method for the design of propellers with flow transition is presented which incorporates transition effects. The designs generated by this method are then optimized in a CFD framework which morphs the blade geometry to improve the ratio of the thrust produced by the propeller to the torque, which corresponds to a higher efficiency. Two design cases are presented: a propeller designed for open water operation, and a propeller design for a small autonomous underwater vehicle.
Advisors/Committee Members: Neu, Wayne L. (committeechair), Brizzolara, Stefano (committeechair), Stilwell, Daniel J. (committee member), Woolsey, Craig A. (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: Marine Propulsion; Transition Modeling; Hydrodynamics
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APA (6th Edition):
Webster, J. A. I. (2019). Design and Analysis of Low Reynolds Number Marine Propellers with Computational Fluid Dynamics (CFD) Transition Modeling. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/93038
Chicago Manual of Style (16th Edition):
Webster, John Ackroyd III. “Design and Analysis of Low Reynolds Number Marine Propellers with Computational Fluid Dynamics (CFD) Transition Modeling.” 2019. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/93038.
MLA Handbook (7th Edition):
Webster, John Ackroyd III. “Design and Analysis of Low Reynolds Number Marine Propellers with Computational Fluid Dynamics (CFD) Transition Modeling.” 2019. Web. 07 Mar 2021.
Vancouver:
Webster JAI. Design and Analysis of Low Reynolds Number Marine Propellers with Computational Fluid Dynamics (CFD) Transition Modeling. [Internet] [Doctoral dissertation]. Virginia Tech; 2019. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/93038.
Council of Science Editors:
Webster JAI. Design and Analysis of Low Reynolds Number Marine Propellers with Computational Fluid Dynamics (CFD) Transition Modeling. [Doctoral Dissertation]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/93038
Virginia Tech
12.
Bassler, Christopher Colby.
Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather.
Degree: PhD, Aerospace Engineering, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/23258
► Ship roll motion has been the subject of many studies, because of the complexities associated with this mode of ship motion, and its impact on…
(more)
▼ Ship roll motion has been the subject of many studies, because of the complexities associated with this mode of ship motion, and its impact on operability, safety, and survivability. Estimation and prediction of the energy transfer and dissipation of the hydrodynamic components, added inertia and damping, is essential to accurately describe the roll motions of a ship. This is especially true for ship operations in moderate to extreme sea conditions. In these conditions, a complex process of energy transfer occurs, which alters the physical behavior of the hydrodynamic components, and ultimately affects the amplitude of ship roll motion. Bilge keels have been used on ships for nearly two centuries, to increase damping and reduce the severity of roll motions experienced by a ship in waves. Because ship motions are more severe in extreme sea conditions, large roll angles may occur. With the possibility of crew injury, cargo damage, or even capsize, it is important to understand the behavior of the roll added inertia and damping for these conditions. Dead ship conditions, where ships may experience excitation from beam, or near beam, seas present a worst case scenario in heavy weather. The behavior of a ship in this condition should be considered in both the design and assessment of seakeeping performance. In this study, hydrodynamic component models of roll added inertia and roll damping were examined and assessed to be unsuitable for accurate prediction of ship motions in heavy weather. A series of model experiments and numerical studies were carried out and analyzed to provide improved understanding of the essential physical phenomena which affect the hydrodynamic components and occur during large amplitude roll motion. These observations served to confirm the hypothesis that the existing models for roll added inertia and damping in large amplitude motions are not sufficient. The change in added inertia and damping behavior for large roll motion is largely due to the effects of hull form geometry, including the bilge keels and topside geometry, and their interactions with the free surface. Therefore, the changes in added inertia and damping must be considered in models to describe and predict roll motions in severe wave environments. Based on the observations and analysis from both experimental and numerical methods, several time-domain model formulations were proposed and examined to model hydrodynamic components of large amplitude roll motions. These time-domain formulations included an analytical model with memory effects, a piecewise formulation, and several possibilities for a bilge keel force model. Although a piecewise model for roll damping was proposed, which can improve the applicability of traditional formulations for roll damping to heavy weather conditions, a further attempt was undertaken to develop a more detailed model specifically for the bilge keel force. This model was based on the consideration of large amplitude effects on the hydrodynamic components of the bilge keel force. Both…
Advisors/Committee Members: Brown, Alan J. (committeechair), Reed, Arthur M. (committee member), Neu, Wayne L. (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: ship motions; seakeeping; roll motion; roll damping; added mass; added inertia; bilge keel; dead ship condition; beam seas; larg
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APA (6th Edition):
Bassler, C. C. (2013). Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/23258
Chicago Manual of Style (16th Edition):
Bassler, Christopher Colby. “Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather.” 2013. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/23258.
MLA Handbook (7th Edition):
Bassler, Christopher Colby. “Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather.” 2013. Web. 07 Mar 2021.
Vancouver:
Bassler CC. Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather. [Internet] [Doctoral dissertation]. Virginia Tech; 2013. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/23258.
Council of Science Editors:
Bassler CC. Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather. [Doctoral Dissertation]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/23258
Virginia Tech
13.
Awasthi, Manuj.
Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities.
Degree: PhD, Aerospace Engineering, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/64158
► Measurements have been performed to understand the sound source mechanism in turbulent boundary layer flow over two and three-dimensional surface discontinuities whose height is smaller…
(more)
▼ Measurements have been performed to understand the sound source mechanism in turbulent boundary layer flow over two and three-dimensional surface discontinuities whose height is smaller than the incoming boundary layer thickness. The work was performed in two different types of boundary layers: a wall-jet flow and a conventional high Reynolds boundary layer. In the wall-jet flow, measurements of far field sound from two-dimensional forward facing steps, gaps with rounded corners and swept forward facing steps with rounded corners were made. The sound from a forward facing step is shown to exhibit effects of non-compactness. Rounding the step corner results in consistent drop in sound levels but the directivity of the sound field remains unchanged. The sound from gaps is dominated by the forward step component and remains unaffected by rounding of the backward step portion. The sound from swept forward facing steps was found to approximately obey an acoustic sweep independence principle up to a sweep angle of 30 deg when the spanwise inhomogeneity in the flow is accounted for using a simple source distribution model. Sweep independence is also observed for steps with corner rounding radii up to 25% of the step height.
The work performed in the high Reynolds number boundary layer included measurements on forward facing steps with rounded corners and a three-dimensional circular embossment with the same height as the forward step. The highest Reynolds number based on discontinuity height achieved in this work was approximately 93,000. The results show that rounding the forward step corner has the same qualitative effect on far field sound as in the wall-jet boundary layer. Quantitatively, for similar boundary layer edge velocity the sound is higher than in the wall-jet flow. The near field measurements show that the separation bubble downstream of the step shrinks as the step corner is rounded while the bubble upstream remains unaffected by it. The unsteady surface force in the lower half of the vertical face of the step was found to be independent of corner rounding. The force on the downstream surface shows similar character within the separation bubble for each rounding but decays faster with increasing downstream distance due to reduced bubble size. The unsteady force measurements were applied to the theory of Glegg et al. (2014) and the resultant of the unsteady forces on the vertical face and downstream surface placed at the top corner of the step is shown to qualitatively describe the far field sound. The acoustic sweep independence principle was applied to the far field sound from the circular embossment and it has been shown that the sound from the three-dimensional geometry can be predicted with reasonable accuracy using sound from a two-dimensional forward step with the same span.
Advisors/Committee Members: Devenport, William J. (committeechair), Paterson, Eric G. (committee member), Glegg, Stewart (committee member), Lowe, Kevin T. (committee member), Alexander, William Nathan (committee member).
Subjects/Keywords: Forward step noise; gap noise; swept forward step noise; circular embossment noise; surface pressure fluctuations and unsteady surface force
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APA (6th Edition):
Awasthi, M. (2015). Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/64158
Chicago Manual of Style (16th Edition):
Awasthi, Manuj. “Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities.” 2015. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/64158.
MLA Handbook (7th Edition):
Awasthi, Manuj. “Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities.” 2015. Web. 07 Mar 2021.
Vancouver:
Awasthi M. Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/64158.
Council of Science Editors:
Awasthi M. Sound Radiated from Turbulent Flow over Two and Three-Dimensional Surface Discontinuities. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/64158
14.
Wu, Jinlong.
Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning.
Degree: PhD, Aerospace Engineering, 2018, Virginia Tech
URL: http://hdl.handle.net/10919/85129
► Reynolds-Averaged Navier–Stokes (RANS) simulations are widely used for engineering design and analysis involving turbulent flows. In RANS simulations, the Reynolds stress needs closure models and…
(more)
▼ Reynolds-Averaged Navier–Stokes (RANS) simulations are widely used for engineering design and analysis involving turbulent flows. In RANS simulations, the Reynolds stress needs closure models and the existing models have large model-form uncertainties. Therefore, the RANS simulations are known to be unreliable in many flows of engineering relevance, including flows with three-dimensional structures, swirl, pressure gradients, or curvature. This lack of accuracy in complex flows has diminished the utility of RANS simulations as a predictive tool for engineering design, analysis, optimization, and reliability assessments. Recently, data-driven methods have emerged as a promising alternative to develop the model of Reynolds stress for RANS simulations. In this dissertation I explore two physics-informed, data-driven frameworks to improve RANS modeled Reynolds stresses. First, a Bayesian inference framework is proposed to quantify and reduce the model-form uncertainty of RANS modeled Reynolds stress by leveraging online sparse measurement data with empirical prior knowledge. Second, a machine-learning-assisted framework is proposed to utilize offline high fidelity simulation databases. Numerical results show that the data-driven RANS models have better prediction of Reynolds stress and other quantities of interest for several canonical flows. Two metrics are also presented for an a priori assessment of the prediction confidence for the machine-learning-assisted RANS model. The proposed data-driven methods are also applicable to the computational study of other physical systems whose governing equations have some unresolved physics to be modeled.
Advisors/Committee Members: Xiao, Heng (committeechair), Paterson, Eric G. (committeechair), Roy, Christopher John (committee member), Lowe, Kevin T. (committee member).
Subjects/Keywords: Turbulence modeling; RANS; Model-form uncertainty; Data-driven; Uncertainty quantification; Bayesian Inference; Machine learning
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APA (6th Edition):
Wu, J. (2018). Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/85129
Chicago Manual of Style (16th Edition):
Wu, Jinlong. “Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning.” 2018. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/85129.
MLA Handbook (7th Edition):
Wu, Jinlong. “Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning.” 2018. Web. 07 Mar 2021.
Vancouver:
Wu J. Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/85129.
Council of Science Editors:
Wu J. Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/85129
Virginia Tech
15.
Cole, Robert Edward.
Numerical Modeling of Air Cushion Vehicle Flexible Seals.
Degree: PhD, Aerospace Engineering, 2018, Virginia Tech
URL: http://hdl.handle.net/10919/83828
► Air cushion vehicle flexible seals operate in a complex and chaotic environment dominated by fluid-structure interaction. An efficient means to explore interdependencies between various governing…
(more)
▼ Air cushion vehicle flexible seals operate in a complex and chaotic environment dominated by fluid-structure interaction. An efficient means to explore interdependencies between various governing parameters that affect performance is through high fidelity numerical simulation. As previous numerical efforts have employed separate iterative partitioned solvers, or have implemented simplified physics, the approaches have been complex, computationally expensive, or of limited utility. This research effort performs numerical simulations to verify and validate the commercial multi-physics tool STAR-CCM+ as a stand-alone partitioned approach for fluid-structure interaction problems with or without a free surface. A dimensional analysis is first conducted to identify potential non-dimensional forms of parameters related to seal resistance. Then, an implicit, Reynolds-averaged Navier-Stokes finite volume fluid solver is coupled to an implicit, nonlinear finite element structural solver to successfully replicate benchmark results for an elastic beam in unsteady laminar flow. To validate the implementation as a seal parameter exploratory tool, a planer bow seal model is developed and results are obtained for various cushion pressures and inflow speeds. Previous numerical and experimental results for deflection and resistance are compared, showing good agreement. An uncertainty analysis for inflow velocity reveals an inversely proportional resistance dependency. Using Abaqus/Explicit, methodologies are also developed for a two-way, loosely coupled explicit approach to large deformation fluid-structure interaction problems, with and without a free surface. Following numerous verification and validation problems, Abaqus is ultimately abandoned due to the inability to converge the fluid pressure field and achieve steady state. This work is a stepping stone for future researchers having interests in ACV seal design and other large deformation, fluid-structure interaction problems. By modeling all necessary physics within a verified and validated stand-alone approach, a designer's ability to comprehensively investigate seal geometries and interactions has never been more promising.
Advisors/Committee Members: Neu, Wayne L. (committeechair), Paterson, Eric G. (committee member), Wang, Kevin Guanyuan (committee member), Smith, Richard W. (committee member).
Subjects/Keywords: fluid-structure interaction; computational fluid dynamics; hydrodynamic resistance; air cushion vehicles
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APA (6th Edition):
Cole, R. E. (2018). Numerical Modeling of Air Cushion Vehicle Flexible Seals. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/83828
Chicago Manual of Style (16th Edition):
Cole, Robert Edward. “Numerical Modeling of Air Cushion Vehicle Flexible Seals.” 2018. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/83828.
MLA Handbook (7th Edition):
Cole, Robert Edward. “Numerical Modeling of Air Cushion Vehicle Flexible Seals.” 2018. Web. 07 Mar 2021.
Vancouver:
Cole RE. Numerical Modeling of Air Cushion Vehicle Flexible Seals. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/83828.
Council of Science Editors:
Cole RE. Numerical Modeling of Air Cushion Vehicle Flexible Seals. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/83828
Virginia Tech
16.
Jones, Matthew Cecil.
Accelerating Conceptual Design Analysis of Marine Vehicles through Deep Learning.
Degree: PhD, Aerospace Engineering, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/89341
► Evaluation of the flow field of a marine vehicle reveals the underlying performance, however, the exact relationship between design features and their impact on the…
(more)
▼ Evaluation of the flow field of a marine vehicle reveals the underlying performance, however, the exact relationship between design features and their impact on the flow field is not well established. The goal of this work is first, to investigate the flow surrounding a self–propelled marine vehicle to identify the significance of various design decisions, and second, to develop a functional relationship between an arbitrary vehicle design and its flow field, thereby accelerating the design analysis process. Near–field wake profiles are computed through simulation, showing good agreement to experimental data. Machine learning is employed to discover the relationship between vehicle geometries and their associated flow fields with two distinct approaches. The first approach directly maps explicitly–specified geometric design parameters to their corresponding flow fields. The second approach considers the vehicle geometries themselves to implicitly–learn the underlying relationships. Once trained, both approaches generate a realistic flow field corresponding to a user–provided vehicle geometry, accelerating the design analysis from a multi–day process to one that takes a fraction of a second. The implicit–parameter approach successfully learns from the underlying geometric features, showing comparable performance to the explicit–parameter approach. With a larger and more–diverse training database, this network has the potential to abstractly learn the design space relationships for arbitrary marine vehicle geometries, even those beyond the scope of the training database.
Advisors/Committee Members: Paterson, Eric G. (committeechair), Devenport, William J. (committee member), Pitt, Jonathan (committee member), Roy, Christopher John (committee member).
Subjects/Keywords: near wake; machine learning; deep learning; adversarial network; OpenFOAM
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APA (6th Edition):
Jones, M. C. (2019). Accelerating Conceptual Design Analysis of Marine Vehicles through Deep Learning. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/89341
Chicago Manual of Style (16th Edition):
Jones, Matthew Cecil. “Accelerating Conceptual Design Analysis of Marine Vehicles through Deep Learning.” 2019. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/89341.
MLA Handbook (7th Edition):
Jones, Matthew Cecil. “Accelerating Conceptual Design Analysis of Marine Vehicles through Deep Learning.” 2019. Web. 07 Mar 2021.
Vancouver:
Jones MC. Accelerating Conceptual Design Analysis of Marine Vehicles through Deep Learning. [Internet] [Doctoral dissertation]. Virginia Tech; 2019. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/89341.
Council of Science Editors:
Jones MC. Accelerating Conceptual Design Analysis of Marine Vehicles through Deep Learning. [Doctoral Dissertation]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/89341
Virginia Tech
17.
Somero, John Ryan.
Structure and Persistence of Surface Ship Wakes.
Degree: 1, Not found, 2021, Virginia Tech
URL: http://hdl.handle.net/10919/101989
► It has long been known that ship wakes are observable by synthetic aperture radar. However, incomplete physical understanding has prevented the development of simulation tools…
(more)
▼ It has long been known that ship wakes are observable by synthetic aperture radar. However,
incomplete physical understanding has prevented the development of simulation tools that
can predict both the structure and persistence of wakes in the ocean environment, which
is critical to understanding both the design and operation of maritime remote sensors as
well as providing tactically relevant operational guidance and awareness of the maritime
domain. It is the focus of this work to develop an end-to-end multi-scale modeling-and simulation
methodology that captures the known physics between the source of disturbance
and the sensor. This includes turbulent hydrodynamics, free-surface effects, environmental
forcing, generation of surface currents and redistribution of surface-active substances,
surface-roughness modification, and simulation of the signature from the ocean surface. The
end-to-end methodology is based upon several customized computational fluid dynamics
solvers and empirical models. The unsteady Reynolds-averaged Navier-Stokes equations, including
models to account for environmental effects and near-surface turbulence, are solved
at full-scale on domains that extend tens of kilometers behind the ship. A parametric study
is undertaken to explore the effects of ship heading, ship propulsion, ocean-wave amplitude
and wavelength, and the relative importance of environmental forcing vs. near-surface turbulence
on the generation of surface currents that are transverse to the wake centerline. Due
to the environmental forcing, the structure of the persistent wake is shown to be a function
of the relative angle between the ambient long-wavelength swell and the ship heading. Ships
operating in head seas observe 1-3 streaks, while ships operating in following seas observe
2 symmetric streaks. Ships operating in calm seas generate similar wakes to those in following
seas, but with reduced wake width and persistence. In addition to the structure of
the persistent wake, the far wake is shown to be dominated by ship-induced turbulence and
surface-current gradients generating a wide center wake. The redistribution of surface films
by surface currents is simulated using a scalar-transport model on the ocean surface. Simulation
of surface-roughness modification is accomplished by solving a wave-action-balance
model which accounts for the relative change in the ambient surface profile by the surface
currents and the damping-effects of surface-active substances and turbulence. Simulated
returns from synthetic aperture radar are generated with two methods implemented. The
first method generates a perfect SAR image where the instrument and platform based errors
are neglected, but the impact of a randomized ocean field on the radar cross section is
considered. The second method simulates the full SAR process including signal detection
and processing. Comparisons are made to full-scale field experiments with good agreement
between the structure of the persistent wake and observed SAR imagery.
Advisors/Committee Members: Paterson, Eric G. (committeechair), Schetz, Joseph A. (committeechair), Brizzolara, Stefano (committee member), England, Scott Leslie (committee member).
Subjects/Keywords: ship wake; Langmuir-type circulations; wave-action balance; surface-roughness modification; synthetic-aperture radar (SAR) imagery
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APA (6th Edition):
Somero, J. R. (2021). Structure and Persistence of Surface Ship Wakes. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/101989
Chicago Manual of Style (16th Edition):
Somero, John Ryan. “Structure and Persistence of Surface Ship Wakes.” 2021. Masters Thesis, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/101989.
MLA Handbook (7th Edition):
Somero, John Ryan. “Structure and Persistence of Surface Ship Wakes.” 2021. Web. 07 Mar 2021.
Vancouver:
Somero JR. Structure and Persistence of Surface Ship Wakes. [Internet] [Masters thesis]. Virginia Tech; 2021. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/101989.
Council of Science Editors:
Somero JR. Structure and Persistence of Surface Ship Wakes. [Masters Thesis]. Virginia Tech; 2021. Available from: http://hdl.handle.net/10919/101989
Virginia Tech
18.
Moon, Chi Young.
Particle Sensing in Gas Turbine Inlets Using Optical Measurements and Machine Learning.
Degree: PhD, Aerospace Engineering, 2021, Virginia Tech
URL: http://hdl.handle.net/10919/101969
► Foreign objects ingested into gas turbines can cause serious damage and degrade their performance. Threats can range from sand, dust, and volcanic ash to condensation…
(more)
▼ Foreign objects ingested into gas turbines can cause serious damage and degrade their performance. Threats can range from sand, dust, and volcanic ash to condensation on ground and high altitude ice crystals. On the component level, experiments and simulations have been performed to establish the performance decrease and risks to continued operations. However, there is a need for a real-time and non-intrusive measurement technique for the ingested mass. While there are established optical methods applicable for this use, these existing methods assume the particle shape to be spherical. The light-particle interaction contains information on the desired parameters, such as particle shape and size. Optical measurements of these interactions, such as scattering and extinction, can serve as "fingerprints" that can be used to estimate particle parameters.
A novel particle measurement technique utilizing supervised machine learning models is presented. The models are trained using a library containing numerically calculated scattering and extinction data. Laser scattering and extinction measurements are used as inputs for the models. This new technique is first demonstrated by sizing particles found in a particle scattering database in the literature. The method's versatility and ruggedness are then demonstrated by accurately estimating the volume flow rate of a spray nozzle spraying water into a research engine. Additionally, the mass flow of sand particles is measured using this technique in a high-speed wind tunnel, in a similar environment to an engine inlet.
Advisors/Committee Members: Lowe, Kevin T. (committeechair), Paterson, Eric G. (committee member), Ma, Lin (committee member), Alexander, William Nathan (committee member).
Subjects/Keywords: foreign object damage; engine health monitoring; laser diagnostics
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APA (6th Edition):
Moon, C. Y. (2021). Particle Sensing in Gas Turbine Inlets Using Optical Measurements and Machine Learning. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/101969
Chicago Manual of Style (16th Edition):
Moon, Chi Young. “Particle Sensing in Gas Turbine Inlets Using Optical Measurements and Machine Learning.” 2021. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/101969.
MLA Handbook (7th Edition):
Moon, Chi Young. “Particle Sensing in Gas Turbine Inlets Using Optical Measurements and Machine Learning.” 2021. Web. 07 Mar 2021.
Vancouver:
Moon CY. Particle Sensing in Gas Turbine Inlets Using Optical Measurements and Machine Learning. [Internet] [Doctoral dissertation]. Virginia Tech; 2021. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/101969.
Council of Science Editors:
Moon CY. Particle Sensing in Gas Turbine Inlets Using Optical Measurements and Machine Learning. [Doctoral Dissertation]. Virginia Tech; 2021. Available from: http://hdl.handle.net/10919/101969
19.
Nastasi, Kevin Michael.
Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness.
Degree: PhD, Aerospace Engineering, 2018, Virginia Tech
URL: http://hdl.handle.net/10919/84931
► As resident space object populations grow, and satellite propulsion capabilities improve, it will become increasingly challenging for space-reliant nations to maintain space situational awareness using…
(more)
▼ As resident space object populations grow, and satellite propulsion capabilities improve, it will become increasingly challenging for space-reliant nations to maintain space situational awareness using current human-in-the-loop methods. This dissertation develops several real-time adaptive approaches to autonomous sensor network management for tracking multiple maneuvering and non-maneuvering satellites with a diversely populated Space Object Surveillance and Identification network. The proposed methods integrate suboptimal Partially Observed Markov Decision Processes (POMDPs) with covariance inflation or multiple model adaptive estimation techniques to task sensors and maintain viable orbit estimates for all targets. The POMDPs developed in this dissertation use information-based and system-based metrics to determine the rewards and costs associated with tasking a specific sensor to track a particular satellite. Like in real-world situations, the population of target satellites vastly outnumbers the available set of sensors. Robust and adaptable tasking algorithms are needed in this scenario to determine how and when sensors should be tasked. The strategies developed in this dissertation successfully track 207 non-maneuvering and maneuvering spacecraft using only 24 ground and space-based sensors. The results show that multiple model adaptive estimation coupled with a multi-metric, suboptimal POMDP can effectively and efficiently task a diverse network of sensors to track multiple maneuvering spacecraft, while simultaneously monitoring a large number of non-maneuvering objects. Overall, this dissertation demonstrates the potential for autonomous and adaptable sensor network command and control for real-world space situational awareness.
Advisors/Committee Members: Black, Jonathan T. (committeechair), Paterson, Eric G. (committee member), Psiaki, Mark L. (committee member), Canfield, Robert Arthur (committee member).
Subjects/Keywords: Sensor Network Management; Remote Sensing; Adaptive Estimation; Astrodynamics; Space Situational Awareness; Autonomy
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APA (6th Edition):
Nastasi, K. M. (2018). Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/84931
Chicago Manual of Style (16th Edition):
Nastasi, Kevin Michael. “Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness.” 2018. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/84931.
MLA Handbook (7th Edition):
Nastasi, Kevin Michael. “Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness.” 2018. Web. 07 Mar 2021.
Vancouver:
Nastasi KM. Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/84931.
Council of Science Editors:
Nastasi KM. Autonomous and Responsive Surveillance Network Management for Adaptive Space Situational Awareness. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/84931
20.
Zhang, Di.
Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics.
Degree: PhD, Aerospace Engineering, 2017, Virginia Tech
URL: http://hdl.handle.net/10919/81137
► Wind energy industry thrived in the last three decades, environmental concerns and government regulations stimulate studies on wind farm location selection and wind turbine design.…
(more)
▼ Wind energy industry thrived in the last three decades, environmental concerns and government regulations stimulate studies on wind farm location selection and wind turbine design. Full-scale experiments and high-fidelity simulations are restrictive due to the prohibitively high cost, while the model-scale experiments and low-fidelity calculations miss key flow physics of unsteady high Reynolds number flows.
A hybrid RANS/LES turbulence model integrated with transition formulation is developed and tested by a surrogate model problem through joint experimental and computational fluid dynamics approaches. The model problem consists of a circular cylinder for generating coherent unsteadiness and a downstream airfoil in the cylinder wake. The cylinder flow is subcritical, with a Reynolds number of 64,000 based upon the cylinder diameter.
The quantitative dynamics of vortex shedding and Reynolds stresses in the cylinder near wake were well captured, owing to the turbulence-resolving large eddy simulation method that was invoked in the wake. The power spectrum density of velocity components showed that the flow fluctuations were well-maintained in cylinder wake towards airfoil and the hybrid model switched between RANS/LES mode outside boundary layer as expected. According to the experimental and simulation results, the airfoil encountered local flow angle variations up to ±50 degrees, and the turbulent airfoil boundary layer remained attached. Inspecting the boundary layer profiles over one shedding cycle, the oscillation about mean profile resembled the Stokes layer with zero mean. Further processing the data through phase-averaging technique found phase lags along the chordwise locations and both the phase-averaged and mean profiles collapsed into the Law of Wall in the range of 0 < y+ < 50. The features of high blade loading fluctuations due to unsteadiness and transitional boundary layers are of interest in the aerodynamic studies of full-scale wind turbine blades, making the model problem a comprehensive benchmark case for future model development and validation.
Advisors/Committee Members: Paterson, Eric G. (committeechair), Lowe, Kevin T. (committee member), Devenport, William J. (committee member), Staples, Anne E. (committee member).
Subjects/Keywords: Hybrid RANS/LES; DES; Wind Energy; Boundary Layer Transition
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APA (6th Edition):
Zhang, D. (2017). Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/81137
Chicago Manual of Style (16th Edition):
Zhang, Di. “Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics.” 2017. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/81137.
MLA Handbook (7th Edition):
Zhang, Di. “Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics.” 2017. Web. 07 Mar 2021.
Vancouver:
Zhang D. Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics. [Internet] [Doctoral dissertation]. Virginia Tech; 2017. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/81137.
Council of Science Editors:
Zhang D. Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics. [Doctoral Dissertation]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/81137
Virginia Tech
21.
He, Long.
Study of Fluid Forces and Heat Transfer on Non-spherical Particles in Assembly Using Particle Resolved Simulation.
Degree: PhD, Mechanical Engineering, 2018, Virginia Tech
URL: http://hdl.handle.net/10919/91400
► Gas-solid flow is fundamental to many industrial processes. Extensive experimental and numerical studies have been devoted to understand the interphase momentum and heat transfer in…
(more)
▼ Gas-solid flow is fundamental to many industrial processes. Extensive experimental and numerical studies have been devoted to understand the interphase momentum and heat transfer in these systems. Most of the studies have focused on spherical particle shapes, however, in most natural and industrial processes, the particle shape is seldom spherical. In fact, particle shape is one of the important parameters that can have a significant impact on momentum, heat and mass transfer, which are fundamental to all processes. In this study particle-resolved simulations are performed to study momentum and heat transfer in flow through a fixed random assembly of ellipsoidal particles with sphericity of 0.887. The incompressible Navier-Stokes equations are solved using the Immersed Boundary Method (IBM). A Framework for generating particle assembly is developed using physics engine PhysX. High-order boundary conditions are developed for immersed boundary method to resolve the heat transfer in the vicinity of fluid/particle boundary with better accuracy. A complete framework using particle-resolved simulation study assembly of particles with any shape is developed. The drag force of spherical particles and ellipsoid particles are investigated. Available correlations are evaluated based on simulation results and recommendations are made regarding the best combinations. The heat transfer in assembly of ellipsoidal particle is investigated, and a correlation is proposed for the particle shape studied. The lift force, lateral force and torque of ellipsoid particles in assembly and their variations are quantitatively presented and it is shown that under certain conditions these forces and torques cannot be neglected as is done in the larger literature.
Advisors/Committee Members: Tafti, Danesh K. (committeechair), Dancey, Clinton L. (committee member), Batra, Romesh C. (committee member), Paul, Mark R. (committee member), Paterson, Eric G. (committee member).
Subjects/Keywords: immersed boundary method; Immersed boundary method; Non-spherical particle; Momentum transfer; Heat transfer; Nusselt number
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APA ·
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APA (6th Edition):
He, L. (2018). Study of Fluid Forces and Heat Transfer on Non-spherical Particles in Assembly Using Particle Resolved Simulation. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/91400
Chicago Manual of Style (16th Edition):
He, Long. “Study of Fluid Forces and Heat Transfer on Non-spherical Particles in Assembly Using Particle Resolved Simulation.” 2018. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/91400.
MLA Handbook (7th Edition):
He, Long. “Study of Fluid Forces and Heat Transfer on Non-spherical Particles in Assembly Using Particle Resolved Simulation.” 2018. Web. 07 Mar 2021.
Vancouver:
He L. Study of Fluid Forces and Heat Transfer on Non-spherical Particles in Assembly Using Particle Resolved Simulation. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/91400.
Council of Science Editors:
He L. Study of Fluid Forces and Heat Transfer on Non-spherical Particles in Assembly Using Particle Resolved Simulation. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/91400
22.
Cadel, Daniel R.
Advanced Instrumentation and Measurements Techniques for Near Surface Flows.
Degree: PhD, Aerospace Engineering, 2016, Virginia Tech
URL: http://hdl.handle.net/10919/72968
► The development of aerodynamic boundary layers on wind turbine blades is an important consideration in their performance. It can be quite challenging to replicate full…
(more)
▼ The development of aerodynamic boundary layers on wind turbine blades is an important consideration in their performance. It can be quite challenging to replicate full scale conditions in laboratory experiments, and advanced diagnostics become valuable in providing data not available from traditional means. A new variant of Doppler global velocimetry (DGV) known as cross-correlation DGV is developed to measure boundary layer profiles on a wind turbine blade airfoil in the large scale
Virginia Tech Stability Wind Tunnel. The instrument provides mean velocity vectors with reduced sensitivity to external conditions, a velocity measurement range from 0ms^-1 to over 3000ms^-1, and an absolute uncertainty. Monte Carlo simulations with synthetic signals reveal that the processing routine approaches the Cramér-Rao lower bound in optimized conditions. A custom probe-beam technique is implanted to eliminate laser flare for measuring boundary layer profiles on a DU96-W-180 wind turbine airfoil model. Agreement is seen with laser Doppler velocimetry data within the uncertainty estimated for the DGV profile.
Lessons learned from the near-wall flow diagnostics development were applied to a novel benchmark model problem incorporating the relevant physical mechanisms of the high amplitude periodic turbulent flow experienced by turbine blades in the field. The model problem is developed for experimentally motivated computational model development. A circular cylinder generates a periodic turbulent wake, in which a NACA 63215b airfoil with a chord Reynolds number Re_c = 170, 000 is embedded for a reduced frequency k = (pi)fc/V = 1.53. Measurements are performed with particle image velocimetry on the airfoil suction side and in highly magnified planes within the boundary layer. Outside of the viscous region, the Reynolds stress profile is consistent with the prediction of Rapid Distortion Theory (RDT), confirming that the redistribution of normal stresses is an inviscid effect. The fluctuating component of the phase- averaged turbulent boundary layer profiles is described using the exact solution to laminar Stokes flow. A phase lag similar to that in laminar flow is observed with an additional constant phase layer in the buffer region. The phase lag is relevant for modeling the intermittent transition and separation expected at full scale.
Advisors/Committee Members: Lowe, Kevin T. (committeechair), Borgoltz, Aurelien (committee member), Devenport, William J. (committee member), Paterson, Eric G. (committee member), Ng, Wing Fai (committee member).
Subjects/Keywords: Doppler global velocimetry; particle image velocimetry; wind turbine aerodynamics; unsteady boundary layers
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APA ·
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MLA ·
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APA (6th Edition):
Cadel, D. R. (2016). Advanced Instrumentation and Measurements Techniques for Near Surface Flows. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/72968
Chicago Manual of Style (16th Edition):
Cadel, Daniel R. “Advanced Instrumentation and Measurements Techniques for Near Surface Flows.” 2016. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021.
http://hdl.handle.net/10919/72968.
MLA Handbook (7th Edition):
Cadel, Daniel R. “Advanced Instrumentation and Measurements Techniques for Near Surface Flows.” 2016. Web. 07 Mar 2021.
Vancouver:
Cadel DR. Advanced Instrumentation and Measurements Techniques for Near Surface Flows. [Internet] [Doctoral dissertation]. Virginia Tech; 2016. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/10919/72968.
Council of Science Editors:
Cadel DR. Advanced Instrumentation and Measurements Techniques for Near Surface Flows. [Doctoral Dissertation]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/72968
. 
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