CFD Online Discussion Forums - Smearing interface for capillary flows using interfoam

Dear Foamers,

I’m completely new at OpenFoam and also new in this Forum, so first I want to say hello to everyone!

I’m working on capillary flows in nano structures and for this I am using the InterFoam solver.
Unfortunately I get strange results for my liquid-Air interface and for this reason I would like to ask for some explanations or hints for this.

My simulation case is describing a 2D rectangular horizontal capillary tube with a T-junction in it and also with different contact angles at the top and bottom wall. Unfortunately my liquid interface is smearing with the time so I am not able to detect the position of the “real” interface.

I have tried different discretization schemes to getting better results but as before the result is not satisfying.

It would be very nice if someone take a look at my case and give me some helpful hints to fix this.

I will post my simulation files below this message and also in this link:

https://www.dropbox.com/sh/swneqv0un...RRPWqyP4a?dl=0

Regards,

M.

My initial conditions:
-----------------------------------------------------------------------------------

For p:

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

internalField uniform 0;

boundaryField
{
Inlet
{
type fixedValue;
value uniform 0;
}

Outlet
{
type fixedValue;
value uniform 0;
}

bottom
{
type fixedFluxPressure;
}

top
{
type fixedFluxPressure;
}

Front
{
type empty;
}

Back
{
type empty;
}
}
----------------------------------------------------------------------------

For u:

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

internalField uniform (0 0 0);

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

Outlet
{
type zeroGradient;
}

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

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

Front
{
type empty;
}

Back
{
type empty;
}
}
--------------------------------------------------------------------

For alpha:

dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{
Inlet
{
type inletOutlet;
value uniform 1;
inletValue uniform 1;
}

bottom
{
type constantAlphaContactAngle;
theta0 50;
limit gradient;
value uniform 0;
}

top
{
type constantAlphaContactAngle;
theta0 35;
limit gradient;
value uniform 0;
}

Outlet
{
type zeroGradient;
}

Front
{
type empty;

Back
{
type empty;
}
}

----------------------------------------------------------

My fvSchemes file:

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
div(rhoPhi,U) Gauss vanLeer;
div(phi,alpha) Gauss vanLeer01;
div(phirb,alpha) Gauss interfaceCompression;
div((muEff*dev(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p_rgh;
pcorr;
alpha.water;
}

----------------------------------------------------------

My fvSolution file:

solvers
{
alpha.water
{
nAlphaCorr 3;
nAlphaSubCycles 3;
cAlpha 1;
}

pcorr
{
solver PCG;
preconditioner DIC;
tolerance 1e-12;
relTol 0;
}

p_rgh
{
solver PCG;
preconditioner DIC;
tolerance 1e-12;
relTol 0.05;
}

p_rghFinal
{
$p_rgh;
tolerance 1e-12;
relTol 0;
}

U
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-12;
relTol 0;
}
}

PIMPLE
{
momentumPredictor no;
nCorrectors 7;
nNonOrthogonalCorrectors 0;
}