[dhineshcecfd]

Dear Foamers,

I am simulating a simple 3D geometry using interFoam. While running interFoam, deltaT is going upto 1e-7 but my actual deltaT is 0.01 and simulation runs for some days : ( Could anyone help me to fix this issue.? I have attached here the snap shot of mesh, U, p_rgh, alpha.water files:

alpha.water:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object alpha.water;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{

INLET
{
type inletOutlet;
inletValue uniform 1;
value uniform 1;
}

OUTLET
{
type inletOutlet;
inletValue uniform 0;
value uniform 0;
}

FACES
{
type inletOutlet;
inletValue uniform 0;
value uniform 0;

}

OBSTACLES
{
type zeroGradient;
}



defaultFaces
{
type empty;
}
}

// ************************************************** *********************** //

U:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
location "0";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
INLET
{
type fixedValue;
value uniform (0 -0.01 0);
}

OUTLET
{
type zeroGradient;

}

FACES
{
type zeroGradient;
}

OBSTACLES
{
type fixedValue;
value uniform (0 0 0);
}


}


// ************************************************** *********************** //

p_rgh:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [1 -1 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{

INLET
{
type zeroGradient;
}

OUTLET
{
type fixedValue;
value uniform 0;
}

FACES
{
type fixedValue;
value uniform 0;

}

OBSTACLES
{
type fixedFluxPressure;
value uniform 0;
}

}

// ************************************************** *********************** //

[pbachant]

Try turning off the automatic time step adjustment in the controlDict first. This may cause your simulation to crash however. Are you running setFields before interFoam to get the initial alpha distribution setup?

[dhineshcecfd]

Thanks for the reply pbachant.. I have tried turning off "adjustable run time" but my courent no became too large and simulation stopped with core dumped error (pls refer screen shot).. is there any other option to try it out?

I am not using setFields Instead I have mentioned water fields in the alpha.water file


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[dhineshcecfd]

Hi All,

I found the solution of the above problem. The problem was with deltaT in controlDict and it was very large when compared to my smallest element in the grid.

Thanks for your answer.

[pbachant]

What are you trying to simulate? It looks like the way you have it setup, you'll have an infinitesimally thin layer of water at the inlet, and that's it.

[dhineshcecfd]

I am just trying to find the permeability of this geometry.. so the water is continuously flowing from inlet to outlet..I will measure pressure drop once the flow reaches steady state

Sent from my Nexus 4 using CFD Online Forum mobile app

[charlescfd]

Originally Posted by dhineshcecfd

Hi All,

I found the solution of the above problem. The problem was with deltaT in controlDict and it was very large when compared to my smallest element in the grid.

Thanks for your answer.

Hello,
I am also facing the same problem. Does the smallest element mean the minimum face area or the minimum volume? Was the solution to your problem was to make the magnitude of delta T equal to minimum face area or the minimum volume?

[UchihaMadara]

Am also looking at a similar problem, could you explain a little bit please!!!

[vivek05]

Originally Posted by charlescfd

Hello,
I am also facing the same problem. Does the smallest element mean the minimum face area or the minimum volume? Was the solution to your problem was to make the magnitude of delta T equal to minimum face area or the minimum volume?

Hi,
Minimum deltaT (time_step) is based on your smallest size of grid in you mesh..if you know your minimum size of your cell you can approximately predict the deltaT based on courant no

[sciFoam]

Originally Posted by vivek05

Hi,
Minimum deltaT (time_step) is based on your smallest size of grid in you mesh..if you know your minimum size of your cell you can approximately predict the deltaT based on courant no

do you leave alone the U magnitude?

[Anthony Danv]

Originally Posted by vivek05

Hi,
Minimum deltaT (time_step) is based on your smallest size of grid in you mesh..if you know your minimum size of your cell you can approximately predict the deltaT based on courant no

May you explain to me in details. I face the same problem. I run in olaFlow solver with solitary wave propagation. the smallest mesh size: 0.1 m in Z direction, Delta T = 0.1 s. Co= 0.5.