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shipman January 20, 2014 02:53

InterPhaseChangeFoam_Help
 
1 Attachment(s)
Dear Foam Users,

I am trying to simulate cavitation phenomena inside of nozzle and using interphasechangefoam. As you know that there are 3 transport models (Merkle, Kunz and Sauer) I have tried all of these 3 models with kwSST turbulence model however i have problems with the obtaining of cavitation region as follows;

1. If i set the initial cond. according to Velocity as follows:
==> 0/U
Code:

internalField  uniform (0 3.104 0);
boundaryField
{
    inlet
    {
        type            fixedValue;
        value          $internalField;
    }
      outlet
    {
        type            pressureInletOutletVelocity;
        phi            phi;
        value          $internalField;
    }
    wall
    {
        type            fixedValue;
        value            uniform (0 0 0);
    }

==>0/P
Code:

internalField  uniform 1e5;
boundaryField
{
  inlet
    {
        type          zeroGradient;
    }
    outlet
    {
        type            fixedValue;
        value          $internalField;
    }
    wall
    {
        type          zeroGradient;
    }
}

cavitation starts to form until to some level, however after that it disappears although flow rate is increasing. I didnt understand why this happens? (as seen in the attached fig.)

2.if i set the initial cond. according to pressure as follows:
==>0/P
Code:

internalField  uniform 1e5;
boundaryField
{
    inlet
    {
        type            fixedValue;
        value          uniform 2.8e5;
    }
    outlet
    {
        type            fixedValue;
        value          $internalField;
    }
  wall
    {
        type          zeroGradient;
    }

==>0/U
Code:

internalField  uniform (0 0 0);
boundaryField
{
    inlet
    {
        type            zeroGradient;
        value          uniform (0 0 0);
    }
    outlet
    {
        type            inletOutlet;
        inletValue      uniform (0 0 0);
    value        uniform (0 0 0);
    }
    wall
    {
        type            fixedValue;
        value            uniform (0 0 0);
    }

in this case no cavitation form obtained. Therefore i am confused. Could someone advice me something or give some insight what kind of reasons can result in these results? I increased mesh number, changed mass transport model( means i tried 3 of models) still gives same results...

In addition; For interphasechange solver (or more generally if we try simulation multiphase with mass transition which initial condition setting is more logical; pressure or velocity based?

Thanks in advance...

shipman January 20, 2014 02:55

Sorry I forgat to say that initial velocity and pressure values are taken from the experiment...


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