| C.S.Venkat
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May 26, 2000 16:23 |
Re: What does M.O.C. mean in CFD and how to do it?
M.O.C., or the "method of Characteristics" uses a charcteristic grid to compute a flow solution. A characteristic, is a line along which the solution of a partial differential equation reduces to the solution of an ordinary differential equation. This is a simplistic, but correct definition of a characteristic. Unfortunately, in practical problems, the characteristic directions cannot be obtained explicitly, as they are themselves dependent on the solution. Thus we have a sort of catch - 22 situation, for these lines must be constructed by recursion. Additionally, there are special problems when the lines converge into a shock wave.
For these reasons, most modern CFD codes are not based directly on the M.O.C. Instead we have schemes such as the Roe scheme, Galerkin Least squares, etc which are much more effective. However, characteristic theory plays a very important role in the development of numerical boundary conditions at the far-field. A study of the M.O.C will also benefit any CFD specialist who aspires to develop improved methods for flow computations.
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