CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM (http://www.cfd-online.com/Forums/openfoam/)
-   -   Wrong boundary conditions? (http://www.cfd-online.com/Forums/openfoam/91874-wrong-boundary-conditions.html)

thomas.g August 25, 2011 05:13

Wrong boundary conditions?
 
1 Attachment(s)
Hello Foamers,

I want to simulate the flow through a heat exchanger and have already implemented the geometry in OpenFoam.
One part of the heat exchanger looks like the letter U. In this area I got the attached result. The picture shows a slide through the pipe.
I am confused about the flow pattern, because I expected an increase of the velocity at the edge of the curved tube.
Can this be caused by the boundary conditions?
Simulation with: SimpleFoam + k-epsilon for turbulence

Boundary conditions:


U:
boundaryField
{

inlet
{
type fixedValue;
value uniform (1.088250128 0 0);
}

outlet
{
type zeroGradient;
}


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

symmetric
{
type symmetryPlane;
}

frontAndBack
{
type empty;
}
}


p:
dimensions [0 2 -2 0 0 0 0];

internalField uniform 101.3;

boundaryField
{
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 101.3;
}

Walls
{
type zeroGradient;
}

symmetric
{
type symmetryPlane;
}

frontAndBack
{
type empty;
}
}

The frontAndBack-Patch is not in use anymore.

Thanks for your help and good ideas,

Thomas

al_pr August 28, 2011 07:17

Hello Thomas,

I am a beginner in OpenFOAM but for me the boundary conditions look okay and I also agree to you that the results look strange. I would would expect an increase of the velocity. The only thing is, I would change the pressure outlet boundary condition to "$internalField" than "uniform 101.23".

What is your convergence criteria and the "symmetric" part of your geometry?

Regards,

Alex


All times are GMT -4. The time now is 11:23.