Strange pressure/velocity fields using buoyantPimpleFoam
 

Hello Foamer,

I am studying the influences of the external flow of exhaustion fan in a helical condenser using bouyantPimpleFoam. My problem consists:

- The domain is a "wind tunnel”;
- The fan is rotating with 162 rad/s;
- The velocity in the inlet is 1 m/s;
- The condenser has a variation of temperature, but its internal flow is not analysed.

The problem is my results seems strange, because p_rgh and U are not uniform as it should be and p has some kind of stain, as it can be seen in the pictures for the time 0.35s.

Attachment 79812

Attachment 79813

Attachment 79814

These are my checkMesh, fvSolution, fvSchemes and boundary conditions for p, p_rgh and U.

checkMesh:

Create time

Checking geometry...
Overall domain bounding box (-0.6624 -0.552 -0.552) (1.26835 0.552 0.552)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (8.72236e-17 -1.89034e-16 1.21992e-16) OK.
Max cell openness = 3.28732e-16 OK.
Max aspect ratio = 7.35925 OK.
Minimum face area = 7.81001e-07. Maximum face area = 0.0149429. Face area magnitudes OK.
Min volume = 3.39861e-10. Max volume = 0.000531389. Total volume = 2.35281. Cell volumes OK.
Mesh non-orthogonality Max: 69.7345 average: 17.2367
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 1.4638 OK.
Coupled point location match (average 0) OK.

Mesh OK.

End

fvSolution:

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
grad(U) cellLimited Gauss linear 1;
}

divSchemes
{
default none;
div(phi,U) bounded Gauss linearUpwindV grad(U);
div(phi,k) bounded Gauss upwind;
div(phi,omega) bounded Gauss upwind;

div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;

div(meshPhi,p) Gauss linear;

div(phi,h) Gauss upwind;
div(phi,e) Gauss upwind;
div(phi,R) Gauss upwind;
div(phi,K) Gauss linear;
div(phi,Ekp) Gauss linear;
div(R) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

wallDist
{
method meshWave;
}

fvSolution:

solvers
{
"rho.*"
{
solver PCG;
preconditioner DIC;
tolerance 0;
relTol 0;
}


p_rgh
{
solver PCG;
preconditioner DIC;
tolerance 1e-8;
relTol 0.01;
}

p_rghFinal
{
$p_rgh;
relTol 0;
}

"pcorr.*"
{
solver GAMG;
smoother DICGaussSeidel;
cacheAgglomeration no;
maxIter 50;

tolerance 1e-2;
relTol 0;

}
"(U|h|e|k|omega|R)"
{
solver PBiCGStab;
preconditioner DILU;
tolerance 1e-6;
relTol 0.1;
}

"(U|h|e|k|omega|R)Final"
{
$U;
relTol 0;
}
}

PIMPLE
{
momentumPredictor yes;
nOuterCorrectors 1;
nCorrectors 2;
nNonOrthogonalCorrectors 0;
}

U:

Uinlet (1 0 0);

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

internalField uniform (1 0 0);

boundaryField
{
inlet
{
type fixedValue;
value uniform $Uinlet;
}

outlet
{
type pressureInletOutletVelocity;
value uniform $Uinlet;
}

wall
{
type noSlip;
}

fan
{
type movingWallVelocity;
value uniform (0 0 0);
}

"wall_cond_.*"
{
type noSlip;
}

ami_2
{
type cyclicAMI;
value $internalField;
}

ami_1
{
type cyclicAMI;
value $internalField;
}
}

p:

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

internalField uniform 1e5;

boundaryField
{
outlet
{
type calculated;
value $internalField;
}

inlet
{
type calculated;
value $internalField;
}

wall
{
type calculated;
value $internalField;
}

fan
{
type calculated;
value $internalField;
}
"wall_cond_.*"
{
type calculated;
value $internalField;
}
ami_2
{

type cyclicAMI;
value $internalField;

}
ami_1
{
type cyclicAMI;
value $internalField;
}
}

p_rgh:

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

internalField uniform 0;

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

inlet
{
type fixedFluxPressure;
value uniform 0;
}

wall
{
type fixedFluxPressure;
value uniform 0;
}
fan
{
type fixedFluxPressure;
value uniform 0;
}
"wall_cond_.*"
{
type fixedFluxPressure;
value uniform 0;
}
ami_2
{

type cyclicAMI;
value $internalField;

}
ami_1
{
type cyclicAMI;
value $internalField;
}

}

I don't know why this is happening and I hope that someone could help me.

can you share your case?
That is hard to tell like this?