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-   -   What does M.O.C. mean in CFD and how to do it? (http://www.cfd-online.com/Forums/main/2107-what-does-m-o-c-mean-cfd-how-do.html)

 LIU, L. May 11, 2000 05:42

What does M.O.C. mean in CFD and how to do it?

As the title. Thanks.

 John C. Chien May 11, 2000 11:10

Re: What does M.O.C. mean in CFD and how to do it?

(1). You should be able to find it in most gas dynamics books. And some books cover the subject in great details, including examples. (2). The method is exact, and it is usually done graphically , by hand or by computer, especially for supersonic inviscid flows.

 Nicola Maceli May 16, 2000 10:02

Re: What does M.O.C. mean in CFD and how to do it?

M.O.C. Method of characteristics

 C.S.Venkat 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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