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buoyantBoussinesqSimpleFoam with porous zone (source term) problem

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Old   May 26, 2015, 09:05
Exclamation buoyantBoussinesqSimpleFoam with porous zone (source term) problem
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Hi everyone,

Apart from previous post using porousBafflePressure for a zero-thickness porous plate, I also wanted to test it out using DarcyForchheimer source term for a constructed porous zone.

Geometry:

So the geometry is the same, a duct (0.6*0.6*3) with a porous zone inside (0.6*0.6*0.1).


0 folder - initial condition:

the most important 3 parameters for setup:

U: walls (fixedValue; uniform (0 0 0));
inlet (fixedValue; uniform (0.88 0 0));
outlet (zeroGradient);

T: walls and outlet (zeroGradient)
inlet (fixedValue, uniform 300);

p_rgh: walls and inlet (fixedFluxPressure, uniform 0)
outlet (fixedValue, uniform 0)


System folder:

However, I found out that the results are not consistent with the experiment The DarcyForchheimerCoeffs I set in fvOptions are obtained from Delta p = -(D*mu*U + 0.5*I*rho*|U|^2 )L:

d d [0 -2 0 0 0 0 0] (6.3e4 0 0);
f f [0 -1 0 0 0 0 0] (17.73 0 0);

coordinateSystem
{
type cartesian;
origin (0 0 0);
coordinateRotation
{
type axesRotation;
e1 (1 0 0);
e2 (0 1 0);
}

My flow direction is along x-axis, and my porosity directions (not quite sure about this) set for e1 e2 are as indicated above. I did change e1 e2 to a different orientation, the results are still quite similar.

I used snappyHexMesh to refine the porous zone, and topoSet to create cell zones for porous block.

My problem is again, results (pressure drop across the porous zone) are not matching with the experiment data. The pressure drop created by using source term is 1/10 of the experiment value, no matter what D value you choose. The convergence plot is good, although T residuals is above 0.1.

Can someone explain what might cause this problem?

Thank you very much.
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openfoam 2.1.x, porous boundary, porous domain

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