Last edited by Samuktilar

Monday, August 3, 2020 | History

4 edition of **Improved artificial dissipation techniques for viscous flow computations** found in the catalog.

Improved artificial dissipation techniques for viscous flow computations

Kyle Frew

- 281 Want to read
- 32 Currently reading

Published
**1996**
by National Library of Canada in Ottawa
.

Written in English

**Edition Notes**

Thesis (M.Sc.) -- University of Toronto, 1996.

Series | Canadian theses = -- Thèses canadiennes |

The Physical Object | |
---|---|

Format | Microform |

Pagination | 1 microfiche : negative. -- |

ID Numbers | |

Open Library | OL16043357M |

ISBN 10 | 0612126420 |

OCLC/WorldCa | 46531735 |

Examples of the various applications of the flow computation techniques are given in the form of computer-generated illustrations. class of techniques. The book is designed to provide readers. The use of higher order turbulence models, and the precise control of levels of artificial dissipation, can improve the accuracy of high Reynolds number flow computations about complex configurations. The main thrust of this investigation is the incorporation of a low Reynolds number compressible form of the.

Numerical experiments with the revised artificial dissipation terms with carefully devised boundary conditions for the dissipation terms have demonstrated that the revised dissipation models are robust and accurate in the calculation of the flow problems which include high aspect ratio grid cells. An improved low-dissipation AUSMPW+ scheme for low MACH number. Simple a posteriori slope limiter (Post Limiter) for high resolution and efficient flow computations Low speed preconditioning and LU-SGS scheme for 3-D viscous flow computations on unstructured grids. Evaluation of artificial dissipation models and their relationship to.

Numerical Computation of Internal and External Flows Volume 2: Computational Methods for Inviscid and Viscous Flows C. Hirsch, Vrije Universiteit Brussel, Brussels, Belgium This second volume deals with the applications of computational methods to the problems of fluid dynamics. Second-order accurate centered and upwind convective flux computation schemes are discussed. The centered Jameson scheme, plus explicitly added artificial dissipation terms are considered. Three artificial dissipation models, namely a scalar and a matrix version of a switched model, and the CUSP scheme are available.

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Jiri Blazek PhD, in Computational Fluid Dynamics: Principles and Applications (Third Edition), Central scheme with artificial dissipation. The central scheme with artificial dissipation is very simple compared to other discretization methods. It is easy to implement with either the Improved artificial dissipation techniques for viscous flow computations book scheme or with both cell-vertex schemes.

For two-dimensional viscous validation of the modified scheme we focus on low Reynolds number computations to amplify the contribution of the viscous terms, along with transonic flow conditions, to lend some importance to the generation of artificial dissipation as by: A numerical dissipation formulation that provides good shock-capturing capability for hypersonic flows is presented.

This formulation is shown to be a crucial aspect of the multigrid method. Solutions are giver for two-dimensional viscous flow over a NACA airfoil and three-dimensional viscous flow. an artificial dissipation formulation for a semi-implicit, pressure based solution scheme for viscous and inviscid flows International Journal of Computational Fluid Dynamics, Vol.

2, No. Numerical prediction of vortical flow over slender delta wingsCited by: COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 79 () NORTH-HOLLAND PHYSICALLY CONSISTENT MODELS FOR ARTIFICIAL DISSIPATION IN TRANSONIC POTENTIAL FLOW COMPUTATIONS George S.

DULIKRAVICH Department of Aerospace Engineering, The Pennsylvania State University, University Park, PAU.S.A. Karl Author: G. Dulikravich, K. Mortara, L. Marraffa. The code was applied to solve the inviscid flow for NACA airfoil and to the viscous flow in the flat plate case. Both cases show improvements in the code solutions.

The preconditioning techniques were developed to improve the robustness and numerical stability of compressible CFD solvers for a large range of artificial dissipation.

The matrix-valued dissipation scheme introduces the least amount of artificial dissipation and should be expected to yield the most accurate solutions on a given mesh. The flux-difference splitting upwind scheme, on the other hand, is more dissipative and, thus, particularly sensitive to grid resolution, but exhibits the best overall.

Thus before trying to evaluate viscous terms properly, we have to minimize the artificial dissipation effect and this can be realized by the use of high-resolution upwind method. Inclusion of all the viscous terms is not a difficult task and probably would require only 10 to 20% more computational time.

An inner loop iteration scheme is used at each time step to account for the nonlinear effects. The computation of unsteady flow through a flat plate cascade subjected to a transverse gust reveals that the choice of grid spacing and the amount of artificial dissipation is critical for accurate prediction of unsteady phenomena.

An improved Roe solver for high order schemes is proposed. • It changes the original Roe solver dissipation term to improve the level of accuracy. • The dissipation term is split into two parts based on acoustic and entropy waves’ information.

• The exact solution of the Riemann problem has been used to validate this solver. What FLOW-3D Does. In FLOW-3D the default method is a first-order, upstream, advection technique that is extremely robust, but which introduces some numerical viscosity. If it is determined that this numerical viscosity is excessive, because sharp velocity profiles must be computed without the luxury of high grid resolution, then a second-order.

Computations of pulsating supercavity flows behind axisymmetric disk cavitators are presented. The method of computation is a finite volume discretization of the equations of mixture fluid motion. Improved accuracy for inviscid and viscous airfoil flows is obtained with the modified eigenvalue scaling.

Slower convergence rates are experienced with the multigrid method using such scaling. The. The viscous ux is a function of both the conserved variables and their gradients.

Therefore, the solution gradients have to be calculated at the ux points. In our solver, the average approach described in reference31 is used to compute the viscous uxes. The procedure to compute the viscous uxes can be described as follows. Reconstruct Q f at the. It is noted that in the computed results the viscous flow about a hull is not wholly developed but it is on the transition stage, since the computations are continued only for T= Dimensionless time, T=tU0 /L, Us is uniform flow velocity and L is ship length) in the Case 1 and for T= in the Case 2.

Dawes, N. W.,“Towards Improved Throughflow Capability: The Use of 3D Viscous Flow Solvers in a Multistage Environment,” ASME Paper GT Dawes, N. W.,“The Simulation of Three-Dimensional Viscous Flow in Turbomachinery Geometries Using a Solution-Adaptive Unstructured Mesh Methodology,” ASME Paper GT American Institute of Aeronautics and Astronautics Sunrise Valley Drive, Suite Reston, VA Despite its numerical challenges, finite element method is used to compute viscous fluid flow.

A consensus on the cause of numerical problems has been reached; however, general algorithms—allowing a robust and accurate simulation for any process—are still missing. Either a very high computational cost is necessary for a direct numerical solution (DNS) or some limiting procedure.

three-dimensional turbopump applications. Numerical simulations of the flow through the Rocketdyne inducer have been successfully carried out by using CFD techniques for solving viscous incompressible Navier-Stokes equations with the source terms in steadily rotating reference frames.

The method of artificial compressibility with a higher-order. artificial viscosity implicitly in the algorithm. – The solution will go unstable unless the artificial viscosity is added explicitly to the calculation. – A typical cases that may need to add the artificial viscosity to the calculation.

• Flow problems with very strong gradients, such as shock. The connection among von Neumann and Richtmyer's artificial dissipation, Godunov method, and the gas-kinetic BGK scheme is discussed, from which the two concepts of dynamical and kinematical.Venkateswaran et al.

[21,22], Ahuja et al. [23], and Senocak and Shyy [24] added isothermal models to improve the accuracy of a numerical solution for cavitation flow.An analytical study of viscous dissipation effect on the fully developed forced convection Couette flow through a parallel plate channel partially filled with porous medium is presented.

A uniform heat flux is imposed at the moving plate while the fixed plate is insulated.