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Showing 1 to 20 of 153 for “"Turbulence models"”.
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Evaluation of Turbulence Models for Unsteady Separation
… separation in the design of flow devices. Turbulence models in combination with the Reynolds-Averaged Navier-Stokes equations are commonly used in the industrial design process due to their low computational cost; however, their performance in predicting steady separations is …
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New turbulence models for indoor airflow simulation
… predictions. The CFD technique requires a turbulence model to correctly calculate indoor air distribution. However, the currently available turbulence models in the literature are either inaccurate or inefficient for the indoor environment predictions. To solve the problem, this thesis …
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Verification of Statistical Turbulence Models in Aerodynamic Flows
… Shear Stress Transport, and k-\u03c9 turbulence models are compared with their CFL3D and FUN3D counterparts. A grid convergence study is performed to measure the change in the results as a function of element size, specifically for the finest meshes. The flows' mean velocity, skin …
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Turbulence models for non-circular ducts and channels
… predictive procedures for flows in which turbulence-driven secondary motion plays an important role. The focus is on fully-developed flows in closed ducts and open channels of various cross-sectional geometries. Two different turbulence models were evaluated: a complete Reynoldsstress- …
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Quantification of structural uncertainties in RANS turbulence models
… 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 determine the RANS turbulent viscosity …
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Study of Second-Order Turbulence Models With Variable Coefficients
Made available in DSpace on 2014-12-14T14:42:15Z (GMT). No. of bitstreams: 1 7913410.pdf: 4283966 bytes, checksum: f931ef6b9d2495623cf2a1280305b31b (MD5) Previous issue date: 1978
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Stochastic estimation of near-wall closure in turbulence models
… estimator, is used to formulate boundary closure models for the numerical large eddy simulation (LES) of turbulence. The stochastic estimation method resolves coherent structure of the wall layer using empirical correlation functions, and provides an accurate estimation of the wall layer …
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Assessment of RANS Turbulence Models for Strut-Wing Junctions
… the TBW concept to be practical. However, the turbulence models used in these studies have not been validated for transonic, high Reynolds number, junction flows. This study intends to assess turbulence models by comparing drag and surface streamlines obtained from experiment and CFD. The test …
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The evaluation of turbulence models using tensor visualization techniques
… Using the glyph, the effectiveness of two turbulence model formulations of the Reynolds stress tensor, the Boussinesq approximation and the Algebraic Reynolds Stress Model (ARSM), are studied. Glyphs based upon these two formulations and experimentally measured Reynolds stresses are …
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Assessment of RANS Turbulence Models for Hypersonic Flat Plates
… approaches using linear eddy viscosity models for turbulence were not designed and optimized with hypersonic flow problems in mind, and thus have weaknesses that are continuously being studied and addressed. This study evaluates the performance of the Menter Shear Stress Transport (SST) …
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Anisotropic Turbulence Models for Wakes in an Active Ocean Environment
A set of second-moment closure turbulence models are implemented for the study of wake evolution in an oceanic environment. The effects of density stratification are considered, and the models are validated against laboratory experiments mimicking the stratified ocean environment, and against …
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CFD Performance of Turbulence Models for Flow from Supersonic Nozzle Exhausts
… the performance of several eddy-viscosity turbulence models for computing supersonic nozzle exhaust flows. These flows are of relevance in the development of future supersonic transport airplane. Flow simulations of exhaust flows from three supersonic nozzles are computed using ANSYS …
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Implementation and Validation of the ζ-F and ASBM Turbulence Models
… efficiency. Consequently, linear eddy viscosity models (LEVM) are used to model turbulence for an increasing number of flow types. LEVM such as <em>k-ε </em>and <em>k-ω</em> provide modeling with little loss of computational efficiency and have proven to be robust. The LEVM that are most common …
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Turbulence models for the numerical prediction of transitional flows with RANSE
Research on turbulence modeling in naval architecture has extensively increased in importance over the years and it is now considered one of the most important ways to accurately compute high Reynolds number flows with Reynolds Averaged Navier-Stokes Equations (RANSE) solvers. In naval …
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Impact of turbulence models and shape parameterization on robust aerodynamic shape optimization
… of this study was to investigate the impact of turbulence models used in RANS simulations on the 2-D airfoil and 3-D wing designs obtained with gradient-based deterministic and robust optimization in transonic, viscous, turbulent flows. The main contribution of this research to the aerodynamic …
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Residual-based turbulence models for incompressible flows in domains with moving boundaries
This dissertation presents residual-based turbulence models for problems with moving boundaries and interfaces. The method is derived employing the Variational Multiscale (VMS) framework, which gives rise to several modeling options that are exploited to obtain accurate turbulence models. To …
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Computation of high-lift aerodynamics using unstructured grids and Reynolds-stress turbulence models
… theapplication of Differential Reynolds Stress Models (DRSM).The method described in this thesis, separates the grid generation processinto two steps: generation of the anisotropic regions and isotropic grid generation.All surfaces are triangulated as part of the anisotropic grid …
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Development and application of low Reynolds number turbulence models for air-cooled electronics
… Navier-Stokes (RANS) equations for momentum and turbulence. RANS models are popular as they are much quicker to solve than time-dependent models such as Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS). At present the majority of thermal design engineers use the standard k-e model …
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Evaluation of RANS-Based Turbulence Models for the Propagation of Stratified Fronts in Buoyancy-Driven Flow
… Navier-Stokes (RANS) approach to turbulence modeling has previously shown limitations in its ability to adequately predict buoyancy-driven f lows, including thermally stratified flow. Inaccuracies in these cases are often attributed to the Reynolds analogy, a simplification of the …
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Numerical Simulations of Flow past a Triangular Airfoil and in a Sweeping Jet Actuator Using Different Turbulence Models
… Navier-Stokes (RANS) equations with a number of turbulence models, namely the SA, SST <em>k-</em><em>ω</em>, and recently developed Wray – Agarwal (WA) model are solved. The computations are compared with the experimental data to assess the accuracy of various turbulence models. Lift coefficient, …
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