Convergence problem in steady state simulation of centrifugal fan in openfoam

hello,

I am new to openfoam and trying to simulate centrifugal fan with steady state, in-compressible, turbulent flow(realizableKE model) MRF approach using simpleFoam solver. The problem is solution is not converging(after not 10000 iterations) and values of U & P are in order of 10^3 & 10^9.

Initial & Boundary conditions

1. P

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

internalField uniform 0;

boundaryField
{
Rotar
{
type zeroGradient;
}

Inlet
{
type fixedValue;
value uniform 84104.28;// atm pressure nearly 1 bar
}

Outlet
{
type zeroGradient;

}

Wall
{
type zeroGradient;
}

}

2.U

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

internalField uniform (0 0 0);

boundaryField
{
Rotar
{
type noSlip;

}

Inlet
{
type pressureInletVelocity;
value uniform (0 0 0);
}

Outlet
{
type flowRateOutletVelocity ;
volumetricFlowRate 0.0452;//=2712 lpm
value uniform (0 0 0);
}

Wall
{
type noSlip;
}
}

3.epsilon

dimensions [0 2 -3 0 0 0 0];

internalField uniform 5.604;

boundaryField
{
Rotar
{
type epsilonWallFunction;
value uniform 5.604;
}

Wall
{
type epsilonWallFunction;
value uniform 5.604;
}

Inlet
{
type fixedValue;
value uniform 5.604;
}

Outlet
{
type zeroGradient;
}
}

4. k

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

internalField uniform 0.91;

boundaryField
{
Rotar
{
type kqRWallFunction;
value uniform 0.91;
}

Wall
{
type kqRWallFunction;
value uniform 0.91;
}

Inlet
{
;
type turbulentIntensityKineticEnergyInlet;
intensity 0.02; //
value uniform 0.91; //
}

Outlet
{
type zeroGradient;
}

}

5.MRF properties

MRF1
{
cellZone Fan;
active yes;

// Fixed patches (by default they 'move' with the MRF zone)
nonRotatingPatches ();

origin (0 0 105);
axis (0 0 1);
omega -50;//477rpm
}

6.fvSchemes

ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss upwind;
div(phi,k) Gauss upwind ;
div(phi,epsilon) Gauss upwind ;
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}
wallDist
{
method meshWave;
}

7.fvSolution

solvers
{
p
{
solver GAMG;
tolerance 1e-02;
relTol 0.05;
smoother GaussSeidel;
nCellsInCoarsestLevel 20;
}

U
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-02;
relTol 0.1;
}

k
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-02;
relTol 0.1;
}

epsilon
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 2;
tolerance 1e-02;
relTol 0.1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 1;
pRefCell 0;
pRefValue 0;
}

relaxationFactors
{
fields
{
p 0.3;
}
equations
{
U 0.7;
k 0.3;
epsilon 0.3;
}
}

whether boundary conditions, units, MRF or tubulent model is going wrong??

OpenFOAM 22-11-19, 1:25 p.m. rohanmajalekar

Hi Rohan,

Can you please go through this completed Case Study by Aashay on similar topic

https://cfd.fossee.in/case-study-project/case-study-run/8

Regards,

Sathish

26-11-19, 11:24 a.m. sathish