Boundary instabilities in thin fluid film using interFoam
 

Dear all,
I'm simulating an open channel flow of water with small depth using the interFoam (laminar) solver, but I'm having problems at the borders of the channel, it looks like the pressure is not behaving well, so it creates big inestable waves on the sides of the channel.

I have tried changing the mesh, schemes, solvers and border conditions with no succes. I hope you could help me find what I'm doing wrong.

The size of the channel is: 7 m length, 0.05 m wide and 0.012 m heigh. It has an inclination of 5.45°. The water initially has a 0.01 m depth and the other part is air.

I attached the different fvSolution and p_rgh that I have tried, also blockMesh, fvScheme and screenshots of how the wave looks like.

For the turbulenceProperties file, I have used laminar and LESModel (for the LESModel, I attached the LESProperties file). Also I have used different Courant numbers (between 0.2 and 0.5) to adjust the time step. I have tried with different cAlpha (between 0.25 and 1), with and without momentumPredictor and I have varied the tolerance, relTol, nOuterCorrectors, nCorrectors.

In the fvScheme I have tried:
-divSchemes
div(phirb,alpha): Gauss interfaceCompression or Gauss linear
-gradSchemes: Gauss linear or leastSquares

alpha.water:
boundaryField
{
entrada
{
type fixedValue;
value uniform 1;
}
lateral-der
{
type zeroGradient;
}
lateral-iz
{
type zeroGradient;
}
salida
{
type inletOutlet;
inletValue uniform 0;
value uniform 0;
}
piso
{
type zeroGradient;
}
atmosfera
{
type inletOutlet;
inletValue uniform 0;
value uniform 0;
}
entrada-at
{
type fixedValue;
value uniform 0;
}
}


The initial velocity field it is (0 0.839937 -0.080137) in the water and (0 0 0) in the air. So the water moves with a velocity of 0.84 m/s paralel to the channel.
U
boundaryField
{
entrada
{
type flowRateInletVelocity;
volumetricFlowRate constant 0.000421876;
value uniform (0 0.839937 -0.080137);
}
lateral-der
{
type fixedValue;
value uniform (0 0 0);
}
lateral-iz
{
type fixedValue;
value uniform (0 0 0);
}
salida
{
type pressureInletOutletVelocity;
value nonuniform List<vector>
}
piso
{
type fixedValue;
value uniform (0 0 0);
}
atmosfera
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}
entrada-at
{
type fixedValue;
value uniform (0 0 0);
}
}