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A comparative study of central and upwind difference schemes using the primitive variables
Author(s) -
Timin Tsai,
Esmail M. Nabil
Publication year - 1983
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.1650030308
Subject(s) - upwind scheme , mathematics , vorticity , reynolds number , stream function , flow (mathematics) , finite difference , numerical diffusion , computational fluid dynamics , finite difference method , hele shaw flow , mathematical analysis , geometry , mechanics , vortex , turbulence , open channel flow , physics , discretization
The use of the velocity‐pressure formulation of the Navier‐Stokes equations for the numerical solution of fluid flow problems is favoured for free‐surface problems, more involved flow configurations, and three‐dimensional flows. Many engineering problems involve such features in addition to strong inertial effects. The computational instabilities arising from central‐difference schemes for the convective terms of the governing equations impose serious limitations on the range of Reynolds numbers that can be investigated by the numerical method. Solutions for higher Reynolds numbers Re > 1000 could be reached using upwind‐difference schemes. A comparative study of both schemes using a method based on the primitive variables is presented. The comparison is made for the model problem of the driven flow in a square cavity. Using a central scheme stable solutions of the pressure and velocity fields were obtained for Reynolds numbers up to 5000. The streamfunction and vorticity fields were calculated from the resulting velocity field and compared with previous solutions. It is concluded that total upwind differencing results in a considerable change in the flow pattern due to the false diffusion. For practical calculations, by a proper choice of a small amount of partial upwind differencing the vorticity diffusion near the walls and the global features of the solutions are not sigificantly altered.