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-   -   Numerical Diffusion in OpenFOAM (http://www.cfd-online.com/Forums/openfoam/92875-numerical-diffusion-openfoam.html)

srikanth_b September 28, 2011 04:50

Numerical Diffusion in OpenFOAM
 
1 Attachment(s)
hi,
I am working with the solver interFoam to simulate bubble rise in a sheared liquid
My settings are as follows
mesh resolution: 10 cells per diameter (3D)
time step: variable ( Courant No: 0.01)
max dt: 1e-6
Calpha :1 (compression on)

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
grad(U) Gauss linear;
grad(alpha1) Gauss linear;
}

divSchemes
{
div(rho*phi,U) Gauss limitedLinearV 1;
div(phi,alpha) Gauss vanLeer;
div(phirb,alpha) Gauss interfaceCompression;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p;
pcorr;
alpha1;
}
I am seeing numerical diffusion and the bubble seems to shred on moving up
It is not really breaking since the broken blobs(yellow thingy's) seems to be of alpha value about .975 and do not have any alpha=0 inside
I have been stuck with this problem for quite some time so any suggestions would be appreciated.
I have also explored interDyMFoam with even worse results
Help!!!!!!
PFA a overlay of various alpha plots


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