[Jingxue Wang]

I am calculating a LES simulation using PISO method. Even I changed the boundary conditions, the calculation always stoped at only the 3rd time step.And the Courant number increased from 2.3 to 15 and then 243 for the first three time intervals. And the following errors occurred:

#0  Foam::error::printStack(Foam::Ostream&) at ???
#1  Foam::sigFpe::sigHandler(int) at ???
#2 ？in “/lib/x86_64-linux-gnu/libc.so.6”
#3 ...

Could anybody meet this problem before?I am really puzzled for this problem!

Thanks in advance!

E-mail:jingxue_wang1@yahoo.co.jp

[Tobi]

Hi,

this is a common error message if something went wrong already in the initialization step. However, without any further information we cannot give you any support. I refer you to the following thread: How to give enough info to get help

[Jingxue Wang]

Hi, Tobi

Thanks for your suggestion!I have posted my question in a new version, which was diecribed more in detail.

Thanks!

[Tobi]

Hi,

to be honest, there are not too much information. However, PISO has a constant dt and I guess in your case it is way too large. Based on the Courant number definition, the only thing that can happen is that your velocity values get larger and larger. Thus the Courant number becomes larger and then you do not fulfill the stability criterion Co < 1. The problem can come from non-sense boundary condition, your mesh, your setup, delta t ...

The first way is to reduce the time step and save each iteration. Check out the results in paraview to get the idea what happens and then decide how to overcome the problem.

[Jingxue Wang]

hi,Tobi

Thanks a lot for your suggestions.!

Could you see my new thread? https://www.cfd-online.com/Forums/openfoam-solving/193898-foam-error-printstack-foam-ostream.html#post666750

There are boundary conditions and discretization schemes.


From Tobi: --> Above thread deleted. Content added below (multiple threads)
================================================== ==================================================
I am calculating a LES simulation using PISO method. Even I changed the boundary conditions, the calculation always stoped at only the 3rd time step.And the Courant number increased from 2.3 to 15 and then 243 for the first three time intervals. And the following errors occurred:
#0 Foam::error:rintStack(Foam::Ostream&) at ???
#1 Foam::sigFpe::sigHandler(int) at ???
#2 ？in “/lib/x86_64-linux-gnu/libc.so.6”
#3 ...

The models is a flat roof buidling inside the wind tunenl. The first cell is 6*e-5m, satisfying the y+<1 in LES. The deltT is 1e-5,satisfying the Co<1.

The boundary conditions and discretization schemes are as follows, where the inlet, outlet, left,right,up,ground are the wind tunnel boundaries, and windward,leftward,leftward,rightward and roof are building surfaces.

//0-p

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

internalField   uniform 0;

boundaryField
{
    INLET
    {
        type           zeroGradient;
    }
    OUTLET
    {
      //type           zeroGradient;
          type            fixedValue;
          value           uniform 0;
    }
    LEFT
    {
         type           zeroGradient;
        // type           symmetryPlane;
    }
    RIGHT
    {
          type           zeroGradient;
       //type           symmetryPlane;
    }
    UP
    {
         type           zeroGradient;
        //type          symmetryPlane;
    }
    GROUND
    {
         type           zeroGradient;
    }
    ROOF
    {
         type           zeroGradient;
    }
    WINDWARD
    {
        type           zeroGradient;
    }
    BACKWARD
    {
         type           zeroGradient;
    }
    LEFTWARD
    {
         type           zeroGradient;
    }
    RIGHTWARD
    {
         type           zeroGradient;
    }
}

//0-U

internalField   uniform (5 0 0);

boundaryField
{
    INLET
    {
        type            fixedValue;
        value           uniform (5 0 0);
    }
    OUTLET
    {
         type           zeroGradient;
        //type            inletOutlet;
        //inletValue      uniform (0 0 0);
        //value           uniform (0 0 0);
    }
    LEFT
    {
        //type          symmetryPlane;
        type            fixedValue;
        value           uniform (0 0 0);
    }
    RIGHT
    {
        //type           symmetryPlane;
        type            fixedValue;
        value           uniform (0 0 0);
    }
    UP
    {
       // type           symmetryPlane;
        type            fixedValue;
        value           uniform (0 0 0);
    }
    GROUND
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    ROOF
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    WINDWARD
    {
         type            fixedValue;
        value           uniform (0 0 0);
    }
    BACKWARD
    {
         type            fixedValue;
        value           uniform (0 0 0);
    }
    LEFTWARD
    {
         type            fixedValue;
        value           uniform (0 0 0);
    }
    RIGHTWARD
    {
         type            fixedValue;
        value           uniform (0 0 0);
    }
}

//fvSchemes

ddtSchemes
{
    default         CrankNicolson 0.9;
}


gradSchemes
{
    default         Gauss linear;
    grad(p)         Gauss linear;
}

divSchemes
{
    default         none;
    div(phi,U)      Gauss LUST grad(U);
    div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

//turbulencepropety

simulationType  LES;

LES
{
    LESModel Smagorinsky;

    turbulence      on;
    printCoeffs     on;

    delta cubeRootVol;

    cubeRootVolCoeffs
    {
        deltaCoeff 1;
    }
}

Thanks for your help!

[Tobi]

Dear Wang,

don't double post threads (see my PM). Take time to ask your question. If you don't take your time, no one else will do it. The pressure BC makes no sense - millions of possible pressures possible. However, you statement: dt = 6e-5 to satisfy Co<1. How do you think that is true? If you have any obstacle, the flow will accelerate somewhere etc (Bernoulli)... and then your Co criterion is not satisfied anymore. Error accumulation can be an outcome.

Good luck.

[Jingxue Wang]

Originally Posted by Tobi

Dear Wang,

don't double post threads (see my PM). Take time to ask your question. If you don't take your time, no one else will do it. The pressure BC makes no sense - millions of possible pressures possible. However, you statement: dt = 6e-5 to satisfy Co<1. How do you think that is true? If you have any obstacle, the flow will accelerate somewhere etc (Bernoulli)... and then your Co criterion is not satisfied anymore. Error accumulation can be an outcome.

Good luck.

Dear Tobi

I understand the point you meant.I will check the boundary conditions,the setup and delta t.

Thank you so much!