[roo1valk]

Good day all,


I am trying to run a simple parallel plate flow case using the icoFoam solver. However, I am getting a strange result for my velocity field, shown in the image below. I have had a look at the icoFoam - Elbow tutorial, which I understand to have similar boundary conditions. I suspect I might be missing something really simple, but cannot figure out what is wrong. I have tried a few different combinations of boundary conditions. Any pointers would be greatly appreciated. My blockMeshDict, p and U files are included below.


My blockMeshDict file body:

scale 1;

vertices
(
(0.01 0.005 -0.1)
(-0.01 0.005 -0.1)
(-0.01 -0.005 -0.1)
(0.01 -0.005 -0.1)
(0.01 0.005 0.1)
(-0.01 0.005 0.1)
(-0.01 -0.005 0.1)
(0.01 -0.005 0.1)
);

blocks
(
hex (0 1 2 3 4 5 6 7) (4 1 40) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
fixedWalls
{
type wall;
faces
(
(1 5 4 0)
(3 7 6 2)
);
}
frontback
{
type empty;
faces
(
(2 6 5 1)
(0 4 7 3)
);
}
inlet
{
type patch;
faces
(
(0 3 2 1)
);
}
outlet
{
type patch;
faces
(
(4 5 6 7)
);
}
);

My boundary conditions for p:

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

internalField uniform 0;

boundaryField
{
fixedWalls
{
type zeroGradient;
}

inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 0;
}

frontback
{
type empty;
}
}


My boundary conditions for U:

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

internalField uniform (0 0 0);

boundaryField
{
fixedWalls
{
type noSlip;
}

inlet
{
type fixedValue;
value uniform (0 0 1);
}

outlet
{
type zeroGradient;
}

frontback
{
type empty;
}
}

[peterhess]

Hello!,

4 cell in x direction is too few. Increase the number to, lets say, 10.

I suppose the y direction is the empty one. In this case one cell is sufficient.

The velocity in z direction should be -1 instead of 1, if the inlet at the top. Else it is right.

The velocity at the outlet should be changed to inletOutlet instead of zeroGradient.

Regards

Peter

[roo1valk]

Hi Peter,

Thank you for your reply. My inlet is at the bottom, thus I kept it at 1 m/s (+Z). Velocity at the outlet is now an inletOutlet boundary condition. I also realized that my fixedWalls (noSlip condition) and frontback (empty condition) was swapped around, i.e. only one cell between my noSlip walls. I made the changes and now it works, screenshot of velocity field attached.

Kind regards,
Johannes