[NiFl]

Hi everybody,

I am trying to simulate an array of microchannels (each 100x100 microns) (in x-y-plane) between two manifolds which are slightly bigger. The liquid is entering through an inlet and exits through a similar outlet, both - in/outlet - point in x-direction.
My mesh is created with gmsh and I use 'transformPoints -scale' to scale it to microns.
I use interFoam to get a multiphase simulation.

My configurations:

alpha1:
boundaryField
{
wall
{
type fixedValue;
value uniform 0;
}
inlet
{
type zeroGradient;
}
outlet
{
type zeroGradient;
}
}

U
internalField uniform (0 0 0);

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

inlet
{
type zeroGradient;
value uniform ( 0 0 0 );
}
outlet
{
type zeroGradient;
value uniform ( 0 0 0 );
}

}

p
boundaryField
{
wall
{
type fixedFluxPressure; // tried also zeroGradient but exploded ;
value uniform 0;
}

inlet
{
type fixedValue;
value uniform 500;
}
outlet
{
type fixedValue;
value uniform 0;
}

}

setFieldsDict

defaultFieldValues
(
volScalarFieldValue alpha1 1
);

regions
(
boxToCell
{
box (-1 -1 -1) (1 1 1e-4);
fieldValues
(
volScalarFieldValue alpha1 0
);
}
boxToCell
{
box (1e-2 1e-2 1e-4) (1 1 1);
fieldValues
(
volScalarFieldValue alpha1 0
);
}
);

So that only my inlet is filled with liquid (phase1) and the rest of the channels is filled with air (phase2).

When I run my case, everythings looks good until I reach something around a second, then my inlet runs dry! Does someone have experience with this problem? Do I have to add a sort of 'basin' on my inlet to supply more liquid or is it due to my BC?

Thanks for your help
Nils

[nimasam]

i recommend for inlet, to use

alpha1: fixedValue 1
U: pressureInletVelocity

[NiFl]

Thanks, works so far, but I still have the impression that there are some difficulties at my outlet...

[NiFl]

Hi ,

just to come to a kind of conclusion:

I changed the alpha1 settings to:

boundaryField
{
wall
{
type fixedValue;
value uniform 0;
}
inlet
{
type fixedValue;
value uniform 1;
}
outlet
{
type inletOutlet;
inletValue uniform 1;
value uniform 1;
}
}

Now I see the Flux with funkyDoCalc and my Massflow Script:

MassFlow
{
valueType patch;
patchName outlet;

variables ( "threshold=0.5;"
"flux=sum(alpha1>threshold?mag(U*Sf() ):0);");
expression "flux";

accumulations (
min
max
average
sum
);
}