[John Degenkolb]

Hi all,

I’m running a transient two-phase flow simulation through a porous medium using the porousInterFoam solver.

Now, I would like to use a boundary condition, with the following properties:
It should be permeable for phase 1 (air), but impermeable for phase 2 (water). An effect like this is known form GoreTex membranes in outdoor clothes.

The porousInterFoam solver calculates the volume fractions of the two phases for every cell. So, as soon this volume fraction passes a value of 0.5 in a cell which is in contact to the boundary, the condition should switch.

For the permeable (not-wall) case I would like to implement a constant pressure condition.

The question is:
Is there a boundary condition capable to do this by default? And if not: Which is the closest existing boundary condition that I could use a basement for programming?

Thank you in advance for any hints and advices to improve my question!

Peter

[nimasam]

i dont know such BC, but a general advice can be use of groovyBC from third party packahe swak4Foam

[John Degenkolb]

Ok, thanks for the reply.

So here I am trying to use groovy BC for the above mentioned problem.
In my 0/U file I've got:

...
upperWall
{
type groovyBC;
value Expression "0";
variables "alphaMatrix{upperWall}=alpha1;"
}
...

(Yes, I'm trying to access values on the same, not on a different patch. I hope it works...)

The error I get is:

Parser Error for driver PatchValueExpressionDriver at "1.1-5": "field alpha1 not existing or of wrong type"
"alpha1"

I also tried with
alphaMatrix{upperWall}=alpha,
alphaMatrix{upperWall}=alpha.water,
alphaMatrix{upperWall}=alpha.matrix,
alphaMatrix{upperWall}=alphawater.
However, it doesn't seem to find the alpha scalarfield.

The input file specifying the initial volume fractions is called alphamatrix:

FoamFile
{
   version 2.0;
    format ascii;
    class volScalarField;
    object alpha.water;
}

Is it possible to access it in groovyBC?

Thank you in advance!
Peter