Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 70 for “"Turbulence Modeling"”.
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Turbulence modeling in hypersonic inlets
… to analyze the performance of different turbulence models when applied to flow through a Mach 7.4 hypersonic inlet. The analysis, which is two-dimensional, is done by comparing computational results from a Parabolized Navier Stokes code, with experimental data. The McDonald Camarata (MC) …
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Turbulence modeling for film cooling flows
An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to …
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Applications of Lie Groups in Turbulence Modeling
… applied to the general two-dimensional k-epsilon turbulence model. Symmetry algebras for the k-epsilon turbulence model have been calculated by Khor'kova. and Verbovetsky. This systematic approach is applied to the specific flow problem of turbulent submerged free plane jets. Similarity solutions …
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Macroscopic Turbulence Modeling and Simulation for Flow Through Porous Media
… out for 75% and 95% porosities. Different inlet turbulence intensities are imposed on the free stream to test the model under different macroscopic boundary conditions. Microscopic RANS solutions for the turbulence quantities ( k and &egr;) are averaged in space and compared with those yielded by …
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Scale adaptive turbulence modeling for in-vessel sodium thermal hydraulics
… At present, large eddy simulation is the only turbulence modeling approach which can sufficiently resolve and predict the mixing behavior of thermal striping, including temperature fluctuation and fluctuation frequencies. The extreme computational cost requirements of large eddy simulation …
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Effects of Turbulence Modeling on RANS Simulations of Tip Vortices
… this thesis is to quantify the effects of RANS turbulence modeling on the resolution of free shear vortical flows. The simulation of aerodynamic wing-tip vortices is used as a test bed. The primary configuration is flow over an isolated finite wing with aspect ratio, , and Reynolds number, . …
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Predictive Turbulence Modeling with Bayesian Inference and Physics-Informed Machine Learning
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 …
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Machine Learning and Field Inversion approaches to Data-Driven Turbulence Modeling
There still is a practical need for improved closure models for the Reynolds-averaged Navier-Stokes (RANS) equations. This dissertation explores two different approaches for using experimental data to provide improved closure for the Reynolds stress tensor field. The first approach uses machine …
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Extending bubble-induced turbulence modeling applicability in CFD through incorporation of DNS understanding
… Multiphase Computational Fluid Dynamics (M-CFD) modeling and simulation techniques provide three-dimensional resolution of complex flow structures, which can be used to improve operation and safety in current systems, while driving optimization and performance enhancement in next generation …
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Quantification of Spalart-Allmaras Turbulence Modeling Uncertainties for Hypersonic Flows Utilizing Output-Based Grid Adaptation
… thesis, uncertainty in the Spalart-Allmaras (SA) turbulence model with the compressible Reynolds-averaged Navier-Stokes (RANS) equations is quantified for steady non-reacting hypersonic flows using a coarse-grained uncertainty metric. Output-based adaptation is utilized to guarantee negligible …
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Aerodynamic and Aeroacoustic Analysis of Low Reynolds Number Propellers Using Higher-Order RANS Transition Turbulence Modeling
… study has introduced a novel RANS transition turbulence model, SSG/LRR-$\omega$-$\gamma$, that is capable of modeling different modes of transition involving natural, bypass, separation-induced and crossflow transition. The model framework uses a Reynolds stress transport model, …
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Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics
… 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 …
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Physics-Informed, Data-Driven Framework for Model-Form Uncertainty Estimation and Reduction in RANS Simulations
… in RANS models have attracted attention in the turbulence modeling community. In this work, I focus on estimating uncertainties stemming from the RANS turbulence closure and calibrating discrepancies in the modeled Reynolds stresses to improve the predictive capability of RANS models. Both …
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Computational Fluid Dynamics Analysis in Support of the NASA/Virginia Tech Benchmark Experiments
… methods of analysis, especially in the area of modeling separated flow. There exists a large demand for high-fidelity experimental data for turbulence modeling validation. Virginia Tech has joined NASA in a cooperative project to design and perform an experiment in the Virginia Tech Stability …
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Neural Operators for Learning Complex Nonlocal Mappings in Fluid Dynamics
Accurate physical modeling and accelerated numerical simulation of turbulent flows remain primary challenges in CFD for aerospace engineering and related fields. This dissertation tackles these challenges with a focus on Reynolds-Averaged Navier--Stokes (RANS) models, which will continue to serve …
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A Computational Study of the Hydrodynamics of Gas-Solid Fluidized Beds
Computational fluid dynamics (CFD) modeling was used to predict the gas-solid hydrodynamics of fluidized beds. An Eulerian-Eulerian multi-fluid model and granular kinetic theory were used to simulate fluidization and to capture the complex physics associated therewith. The commercial code ANSYS …
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Computational Fluid Dynamics Simulations of Hydraulic Energy Absorber
… of the energy absorber, more sophisticated modeling approaches may be needed. In this research, a steady, two-phase calculation with basic turbulence modeling was used as a first assessment. The two-phase model was used to investigate cavitation effects. Unsteady and advanced turbulence …
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Statistical Analysis of High-Order Moments from Direct Numerical Simulation of a Turbulent Boundary Layer
… boundary layer statistics are important for turbulence modeling efforts and insight into the nature of turbulent flow. In this thesis, a complete database of third-, fourth-, and fifth-order central velocity moments is presented. The statistics were extracted from flow field data from a …
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A neutron activation analysis investigation of traceable elements from automobile exhaust in roadside soil and vegetation
… neutron activation studies of atmospheric and turbulence modeling and possibly for following biological effects of automobile traffic.
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