Improved Artificial Viscosity for High Reynolds Number K-e Turbulence Model

Improved Artificial Viscosity for High Reynolds Number K-e Turbulence Model PDF Author: Tawit Chitsomboon
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Improved Artificial Viscosity for High Reynolds Number K-e Turbulence Model

Improved Artificial Viscosity for High Reynolds Number K-e Turbulence Model PDF Author: Tawit Chitsomboon
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Effects of Artificial Viscosity on the Accuracy of High-Reynolds-number K-e Turbulence Model

Effects of Artificial Viscosity on the Accuracy of High-Reynolds-number K-e Turbulence Model PDF Author: Tawit Chitsomboon
Publisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 24

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Improved Two-equation K-omega Turbulence Models for Aerodynamic Flows

Improved Two-equation K-omega Turbulence Models for Aerodynamic Flows PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 40

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A New K-[epsilon] Eddy Viscosity Model for High Reynolds Number Turbulent Flows

A New K-[epsilon] Eddy Viscosity Model for High Reynolds Number Turbulent Flows PDF Author:
Publisher:
ISBN:
Category : Reynolds stress
Languages : en
Pages : 36

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A Critical Comparison of Several Low Reynolds Number K-epsilon Turbulence Models for Flow Over a Backward Facing Step

A Critical Comparison of Several Low Reynolds Number K-epsilon Turbulence Models for Flow Over a Backward Facing Step PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 16

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Low Reynolds Number Multiple-time-scale Turbulence Model and Calculations of Steady and Pulsating Shear Layers

Low Reynolds Number Multiple-time-scale Turbulence Model and Calculations of Steady and Pulsating Shear Layers PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 42

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Computational Methods for Turbulent, Transonic, and Viscous Flows

Computational Methods for Turbulent, Transonic, and Viscous Flows PDF Author: Jean-André Essers
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 376

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A New Hypothesis on the Anisotropic Reynolds Stress Tensor for Turbulent Flows

A New Hypothesis on the Anisotropic Reynolds Stress Tensor for Turbulent Flows PDF Author: László Könözsy
Publisher: Springer Nature
ISBN: 3030606031
Category : Technology & Engineering
Languages : en
Pages : 517

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Book Description
This self-contained, interdisciplinary book encompasses mathematics, physics, computer programming, analytical solutions and numerical modelling, industrial computational fluid dynamics (CFD), academic benchmark problems and engineering applications in conjunction with the research field of anisotropic turbulence. It focuses on theoretical approaches, computational examples and numerical simulations to demonstrate the strength of a new hypothesis and anisotropic turbulence modelling approach for academic benchmark problems and industrially relevant engineering applications. This book contains MATLAB codes, and C programming language based User-Defined Function (UDF) codes which can be compiled in the ANSYS-FLUENT environment. The computer codes help to understand and use efficiently a new concept which can also be implemented in any other software packages. The simulation results are compared to classical analytical solutions and experimental data taken from the literature. A particular attention is paid to how to obtain accurate results within a reasonable computational time for wide range of benchmark problems. The provided examples and programming techniques help graduate and postgraduate students, engineers and researchers to further develop their technical skills and knowledge.

Improved Reynolds-Stress Modeling for Adverse-Pressure-Gradient Turbulent Boundary Layers in Industrial Aeronautical Flow

Improved Reynolds-Stress Modeling for Adverse-Pressure-Gradient Turbulent Boundary Layers in Industrial Aeronautical Flow PDF Author: Gustave Sporschill
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
This work seeks to improve the prediction of turbulent boundary layer flows under adverse pressure gradients (APG) encountered in the aeronautical industry, especially towards the trailing edge of wings. Indeed, the inaccurate prediction of such flows results in inaccurate predictions of aircraft performance and of the limits of the flight domain. To reduce the design margins and enable optimal aircraft geometries, the reliability of turbulence models in APG boundary layers has to be improved.The relevance of second-moment closures of the RANS equations, also called Reynolds-stress models (RSM), aiming at reproducing more accurately the physics of the flow, is therefore assessed for industrial use. Three Reynolds-stress models that differ in their near-wall modelling and in their length-scale providing equation, namely the EB-RSM, the SSG/LRR-omega RSM and the SSG-omega ATAAC RSM, are first benchmarked on two academic test cases, a flat plate and the APG boundary layer at equilibrium of the Skåre & Krogstad experiment, against the Spalart-Allmaras model and the reference data. These academic cases highlight the fundamental differences between the models and their impact on the profiles and integral quantities of the boundary layer. In particular, the Reynolds-stress profiles and the turbulence budgets in the flat plate test case demonstrate the effectiveness of near-wall modelling. However, the Skåre & Krogstad test case shows the necessity to improve the prediction of velocity profiles in the log region and of skin friction in strong APG flows, despite an excellent prediction of the boundary layer growth.A correction for the log-law region, corresponding to a local recalibration of the model constants in APG regions, is first explored to ensure the correct velocity gradient in APG log layers. The correction is investigated with the Spalart-Allmaras model using a NACA 4412 test case. Despite satisfactory results, the correction is shown to be difficult to generalise to other models and that its impact on the flow prediction is limited to low-Reynolds-number cases, thus restricting its relevance for the aeronautical industry.The two-equation eddy-viscosity models and RSMs are shown to be incompatible with the square-root layer, which progressively grows at the outer end of the log layer in APG boundary layers. A correction locally introducing a pressure-diffusion term is therefore investigated analytically and assessed on the RSMs considered using the Skåre & Krogstad test case. A new model, the EB-RSM-dP, is here defined as a corrected version of the EB-RSM and exhibits improved predictions regarding the velocity and Reynolds-stress profiles and the boundary layer quantities.The standard and corrected RSMs are compared to the Spalart-Allmaras model on an application case, the Common Research Model, representative of a commercial aircraft, and demonstrate the relevance of such models for the aeronautical industry with improved pressure distribution on the wing and reduced errors in the drag-due-to-lift predictions. The square-root-law correction is here validated with the SSG/LRR-omega-dP of Knopp et al. (2018) and the newly developed EB-RSM-dP, and shows significant improvement of the aerodynamic load on the wing, and of both the lift and drag predictions for the highest Reynolds number configuration, compared to the uncorrected models. This study also highlights the strong impact of the activation region of the correction on the results.

Calculation of Complex Turbulent Flows

Calculation of Complex Turbulent Flows PDF Author: George Tzabiras
Publisher: Witpress
ISBN:
Category : Science
Languages : en
Pages : 424

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Book Description
A selection of invited chapters focusing on developments in the application of Computational Fluid Dynamics (CFD) to compressible or incompressible flows dominated by turbulence effects. These may be applied to complex geometrical configurations or flow-fields in simpler geometries requiring higher-order turbulence modelling, or suitably modified low-order models, to calculate crucial parameters such as instabilities, transition, separation, accurate description of velocity and scalar fields, and local and total forces.