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 116 for “"Reynolds Averaged Navier-Stokes (RANS)"”.
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Geometry-Aware Modeling of Rough-Wall Turbulence Using Reynolds-Averaged Navier-Stokes (RANS) Frameworks
… role in drag prediction, energy efficiency, and transport processes in internal and external flows. Despite extensive research, the representation of roughness effects in Reynolds-Averaged Navier–Stokes (RANS) turbulence models remains fundamentally challenging. Classical approaches rely on …
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Quantification of structural uncertainties in RANS turbulence models
… model for the structural uncertainties in Reynolds averaged Navier-Stokes (RANS) turbulence models. This approach solves an inference problem by comparing the results of RANS calculations to direct numerical simulation. The adjoint method is used to efficiently solve an inverse problem to …
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Experimental and Numerical Study of Air Flows in a Full Scale Room
Different turbulence models based on the Reynolds-Averaged Navier-Stokes (RANS) method and the Large Eddy Simulation (LES) with dynamical subgrid model were evaluated with the experimental data from the VPSTV measurements. The LES provided the best predictions for the three ventilation rates while …
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Design and Numerical Evaluation of a Counter- Rotating Compressor in the Absence of Boundary Layer Control: Part II
… two-dimensional, and three dimensional Reynolds averaged Navier-Stokes (RANS) analyses were conducted to verify the design. Additionally, splitter blades were introduced in the first stage rotor as a means of providing mechanical flow control. The two-dimensional analysis indicated that …
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Validation of interpolative interfaces for rotorcraft applications
… and wind tunnel data. Tenasi is an unstructured, Reynolds Averaged Navier-Stokes (RANS) solver developed at the SimCenter: National Center for Computational Engineering, located at the University of Tennessee at Chattanooga. Steady-state results for the isolated ROBIN fuselage and unsteady results …
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Large Eddy Simulation Based Turbulent Flow-induced Vibration of Fully Developed Pipe Flow
… Commercial FSI software packages are based on Reynolds Averaged Navier-Stokes (RANS) fluid models, which do not compute the instantaneous fluctuations in turbulent flow. This thesis presents an FSI approach based on Large Eddy Simulation (LES) flow models, which do compute the instantaneous …
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Machine Learning and Field Inversion approaches to Data-Driven Turbulence Modeling
… 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 learning to learn a …
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Prediction of Noise Associated with an Isolated UAV Propeller
… Simulation (LES) coupled with Unsteady Reynolds-Averaged Navier-Stokes (RANS) solver, is adopted on an isolated propeller modeled from the commercial DJI Phantom II 9450 propeller. The Spalart-Allmaras one equation turbulence model with rotation/curvature correction is used. The …
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Drag Reduction by Polymeric Additive Solutions
… the evaluation of one of the newest viscoelastic Reynolds Averaged Navier-Stokes (RANS) turbulence models. Based on the k−ε−v 2−f framework, this model describes the viscoelastic effects of polymer additives using the Finitely Extensible Nonlinear Elastic-Peterlin (FENEP) constitutive model. To …
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Stabilized finite elements for compressible turbulent Navier-Stokes
… solver for compressible turbulent flows. The Reynolds averaged Navier-Stokes (RANS) equations and modified Spalart-Almaras (SA) turbulence model are discretized using the streamline/upwind Petrov-Galerkin (SUPG) scheme. A fully implicit methodology is used to obtain steady state solutions or …
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Modeling Outdoor Air Pollution and the Urban Form
… thesis develops a solver for aerial pollutant transport by adding a passive-scalar transport equation to buoyantBoussinesqPimpleFoam, the OpenFOAM transient solver for buoyant, turbulent flow of incompressible fluids, with Reynolds Averaged Navier-Stokes (RANS) turbulence modeling. It then …
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Comparison of RANS Modeling to Dual-Plane PIV Measurements of the Turbulent Tip Vortex Trailed from a Hovering Rotor
<p>Numerical simulations using the Reynolds-Averaged Navier-Stokes (RANS) equations were conducted to study the development and turbulent decay of the tip vortices in the wake produced by a hovering rotor. The computational results were compared to detailed, dual plane Particle Image Velocimetry …
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Quantification of Spalart-Allmaras Turbulence Modeling Uncertainties for Hypersonic Flows Utilizing Output-Based Grid Adaptation
… (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 numerical error with complex flow …
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Neural Operators for Learning Complex Nonlocal Mappings in Fluid Dynamics
… tackles these challenges with a focus on Reynolds-Averaged Navier--Stokes (RANS) models, which will continue to serve as the backbone for many practical aircraft applications. Specifically, in RANS turbulence modeling, the challenges include developing more efficient ensemble filters to …
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A Numerical and Experimental Evaluation of the Turbulent Heat Flux in a Heated Jet in Crossflow
… gradient diffusion hypothesis, fundamental to Reynolds-Averaged Navier-Stokes (RANS) models, is evaluated.</p>
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Computational analysis of plasma actuation for control of shock-laden flows in scramjet isolators
Scramjets offer transformative capabilities for hypersonic propulsion, but are limited by instabilities associated with shock wave-boundary layer interactions (SWBLIs). These interactions can diminish engine performance and cause unstart, an aerodynamic phenomenon that can have catastrophic …
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Adjoint-based optimization of U-bend channel flow using a multi-fidelity eddy viscosity turbulence model
… to low-fidelity simulation methods, such as Reynolds Averaged Navier Stokes (RANS), due to current computational capabilities. However, RANS has been shown to lack sufficient accuracy for certain flows. This thesis presents CFD simulation of a 180 degree U-bend square duct using low-fidelity …
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Numerical prediction of the maneuvering characteristics of submarines operating near the free surface
A method for coupling a Reynolds-averaged Navier-Stokes (RANS) computer code with an inviscid panel code to predict the maneuvering characteristics of submarines operating near the free-surface has been developed. The RANS code calculates the flow field immediately surrounding and in the wake of …
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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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An Assessment of the CFD Effectiveness for Simulating Wing Propeller Aerodynamics
… aims to compare computational results from a Reynolds-Averaged Navier-Stokes (RANS) method, StarCCM+, and a vortex lattice method (VLM), VSP Aero. Two configurations that are analysed are 1) WIPP Configuration (Workshop for Integrated Propeller Prediction) 2) APROPOS Configuration. For WIPP, …
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