[dmck]

hi

I want to use a time-varying pressure as my inlet condition, for an unsteady, compressible, case in a square duct. I was planing to use sonicFoam

I would like to add the time-varying pressure to the shockTube example, basically just changing the pressure. I looked at a tutorial on this, which used the timeVaryingTotalPressure, BC and which read the data from a file.

My question is can I run this in the setFields dict? to get the time-varying part along with the initial conditions for the rest of the mesh?

Or how could I achieve this?

Any advice would be useful

David

[elvis]

Hi,

what about swak4foam
http://openfoamwiki.net/index.php/Contrib/swak4Foam

http://openfoamwiki.net/index.php/Contrib_groovyBC
http://openfoamwiki.net/index.php/Co...funkySetFields

here you can read more swak4Foam-Gentle introduction and new developments
http://www.openfoamworkshop2013.org/...dGschaider.tar

[dmck]

thanks for the information elvis

I've been trying to get up to speed with groovy bc and funky fields, I'm not sure I need to use these as firstly the field is uniform, its just the initial pressure wave is nonuniform, I thought the timeVaryingTotalPressure bc would be sufficient to the inlet.

or does anyone think this is wrong?

I used the timeVaryingTotalPressure inlet bc and was able to input the pressure wave that I want, however I did this for a square, straight pipe using pimpleFoam. I did this to learn how to input the pressure wave.

but when I tried to do the same thing using sonicFoam I could not get the simulation to run I got the following error,

#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2 in "/lib/libc.so.6"
#3 void Foam::divide<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh>(Foam::GeometricField<Foam::Vect or<double>, Foam::fvsPatchField, Foam::surfaceMesh>&, Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoCentralFoam"
#4 Foam::tmp<Foam::GeometricField<Foam::Vector<double >, Foam::fvsPatchField, Foam::surfaceMesh> > Foam:perator/<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh>(Foam::GeometricField<Foam::Vect or<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoCentralFoam"
#5
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoCentralFoam"
#6 __libc_start_main in "/lib/libc.so.6"
#7
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoCentralFoam"
Floating point exception

any ideas? I think I might have an issue with my initial conditions

I have set my initial pressure with timeVaryingTotalPressure, fixed value for the outlet

I then used the setFields command to set the pressure and initial conditions for the rest of the mesh. is this the correct thing to do?

any advice is welcome

thanks

[dmck]

update on previous post

I'm getting an error which I believe says I'm trying to divide by zero somewhere.

since I was able to run the time varying pressure for an incompressible case and not able to run it for a compressible case, I'm guessing I have an issue with compressibility.

since rho = p*psi and psi = 1/(R*T)

I need to incorporate T, using the isentropic relationship I calculated t for each corresponding time step - based on the pressure ratio p/p0

I have then added this file for the initial T folder using the time varying uniform value

does this seem reasonable?

FYI I want to simulate the movement of a pressure wave through a duct, I have experimental data for the pressure wave at a the inlet point.


any thoughts on my BC's? I'm guessing thats were the issue is?


I'm lacking in experience and would appreciate some assistance, some general explanation would be great

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    inlet      
    {
       
       type timeVaryingUniformFixedValue;
        fileName "$FOAM_CASE/constant/p0vsTime";
        outOfBounds clamp;
    
    }
wall
    {
        type            zeroGradient;
    }

    outlet     
    {
        type            fixedValue;
        value           uniform 101325;
    }

  

   
}

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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 1;

boundaryField
{
     inlet           
    {
        type timeVaryingUniformFixedValue;
        fileName "$FOAM_CASE/constant/t0vsTime";
        outOfBounds clamp;
     }

   wall           
       {
        type           zeroGradient;
       }

   outlet
      {
        type           zeroGradient;//fixedValue;
        //value         uniform 291;   
      } 
}

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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (0 0 0);

boundaryField
{
    inlet      
    {
        type            pressureInletOutletVelocity;
        value           uniform (0 0 0);
    }

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

    outlet    
    {
         type            inletOutlet;
        inletValue      uniform (0 0 0);
        value           uniform (0 0 0);
    }

   // outlet2   
    //{
      //  type            inletOutlet;
        //inletValue      uniform (0 0 0);
        //value           uniform (0 0 0);
    //}

   
}

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

[dmck]

I have managed to solve my issue, for my timeVaryingFixedValue files I had initial values which were t0=0 and p0=0, when I changed this to at t0=0, p0=101325 everything ran as expected.

[Sakun]

Originally Posted by dmck

I have managed to solve my issue, for my timeVaryingFixedValue files I had initial values which were t0=0 and p0=0, when I changed this to at t0=0, p0=101325 everything ran as expected.

Hi,



is it possible to have a look on your case file ?



thanks in advance