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hg2lf July 25, 2013 12:39

some error using rhoCentralFoam
2 Attachment(s)
Hello all,
I have used rhoCentralFoam to calculate a supersonic nozzle. When I use the upwind scheme, it's all right. But when I change the interpolation scheme to the second order scheme, such as quadraticUpwind, there is a zone next to the wall boundary in which the velocity is lager than the main steam.See the attachment, the two figures show the mach number distribute in the nozzle.
Could someone tell me that why does this happen?

The following is the fvSchem file:

fluxScheme Kurganov;

default Euler;

default Gauss linear;

default none;
div(tauMC) Gauss linear;
div(phi,k) Gauss Minmod phi 1;

default Gauss linear corrected;

default linear;

interpolate(rho) quadraticUpwindFit phi 1;

reconstruct(rho) quadraticUpwindFit 1;
reconstruct(U) quadraticUpwindFit 1;
reconstruct(T) quadraticUpwindFit 1;
reconstruct(K) quadraticUpwindFit 1;

reconstruct(rho) upwind;
reconstruct(U) upwind;
reconstruct(T) upwind;

reconstruct(rho) Minmod;
reconstruct(U) MinmodV;
reconstruct(T) Minmod;
reconstruct(Yi) Minmod;

reconstruct(rho) linearUpwind phi;
reconstruct(U) linearUpwindV phi;
reconstruct(T) linearUpwind phi;
reconstruct(K) linearUpwind phi;

default corrected;

immortality July 26, 2013 21:06

Is you mesh fine enough near wall?
Does it occur in linearUpwind too?
Or Have you found out the reason?

hg2lf July 27, 2013 02:37

The case file is too large to upload. I'm not sure whether the mesh is fine enough. It occur in any other scheme except upwind. But the un-physical solution is not in the boundary area, and it develops from the throat. I'll go on to find out the reason. Best regards.

hg2lf July 27, 2013 10:55

It seems as it linearUpwind scheme works well.

immortality July 27, 2013 13:56

how did you make the mesh?
then the problem is resolved?:)

hg2lf July 30, 2013 01:10

Sorry, there comes the latest news, the problem haven't been solved. The finest mesh is the one associated with the characteristc line.

hg2lf July 31, 2013 12:58

If I using an apreciate discrete schem to solve the subsonic part of the flow well, then it will be fine, Because the high value region develops from this part.

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