CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (http://www.cfd-online.com/Forums/openfoam-solving/)
-   -   This result reasonable help me (http://www.cfd-online.com/Forums/openfoam-solving/60523-result-reasonable-help-me.html)

 zou_mo August 15, 2005 23:55

I compute the motion of threee

I compute the motion of threee bubbles with interFoam. The cGamma is 1.5 for 3D case. From the following jpg figure, we can find some dirty fragments. These fragments may be introduced by the algorithm embedded in interFoam? I have not got idea to solve this problem. Can anyone give me any advie?

time=0.1s and time=.35s:

http://www.cfd-online.com/OpenFOAM_D...ages/1/965.jpg

http://www.cfd-online.com/OpenFOAM_D...ages/1/966.jpg

Thanks.

 zou_mo August 16, 2005 00:05

The result for the single mode

The result for the single mode RT instability is as follows:

http://www.cfd-online.com/OpenFOAM_D...ages/1/968.jpg

The interface is beautiful, yet.

 henry August 16, 2005 04:22

It is not clear that those fra

It is not clear that those fragments are incorrect, they may be a natural consequence of a break-up process caused by the up-draft in the wake of the middle bubble but they may also be numerical as you suggest. What schemes are you using for the terms of the U an gamma equations?

 zou_mo August 16, 2005 04:36

The scheme list: ddtSchemes

The scheme list:
ddtSchemes
{
// Default scheme
default Euler;
}

{
default Gauss linear;
}

// Convection discretisation schemes
divSchemes
{
div(rho*phi,U) Gauss upwind;
div(phi,gamma) Gauss Gamma201 0.2;
div(phirb,gamma) Gauss Gamma201 1;
}

// Laplacian discretisation schemes
laplacianSchemes
{
// Default scheme
default Gauss linear corrected;
}

// Interpolation schemes
interpolationSchemes
{
// Default scheme
default linear;
}

{
// Default scheme
default corrected;
}

// Calculation of flux
fluxRequired
{
// Create storage for flux for all solved variables?
default no;
pd;
pcorr;
gamma;
}

I will try to do some tests with different schemes.

Thanks.

 henry August 16, 2005 04:49

I don't think your choice of s

I don't think your choice of schemes are appropriate for thise case, in particular upwind on U will cause a lot of unnecessary damping and given that your case is low Re you could probably use linear of if that gives trouble Gamma2V 1. However, this will not affect the fragmentation of the interface, to see if this is real or numerical try with

div(phi,gamma) Gauss Gamma01 1;
div(phirb,gamma) Gauss Gamma01 1;

 All times are GMT -4. The time now is 18:16.