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Pressure won't converge in SRFSimpleFoam

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Old   July 23, 2019, 19:25
Default Pressure won't converge in SRFSimpleFoam
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Ziyao LIu
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Hey guys,

I am working on a rotating disk case. I am trying to simulate the velocity field with SRFSimpleFoam. The solver was modified for concentration simulation, but the velocity and pressure part is exactly the same as SRFSimpleFoam.

It works fine when I have a low angular velocity(1 r.p.m.) or a relatively large kinematic viscosity(1e-2). But when I have a higher angular velocity(146 r.p.m.) and lower kinematic viscosity(1e-5), the pressure does not converge and it seems unstable.

The flow in my case has a Reynolds number of 1e4. Which should be in laminar region for rotating disk flow.
I have attach some case file here.

PHP Code:
[CODE]
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  plus                                  |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    
version     2.0;
    
format      ascii;
    class       
dictionary;
    
location    "constant";
    
object      SRFProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

SRFModel        rpm;

origin          (0 0 0);
axis            (0 0 1);

rpmCoeffs
{
    
rpm         146;
}


// ************************************************************************* //[/CODE] 
Here is the transport properties
PHP Code:
[CODE]
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    
version     2.0;
    
format      ascii;
    class       
dictionary;
    
location    "constant";
    
object      transportProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

//  Units: l0 = unit of the point field (1cm), t0 = 1s  //

transportModel  Newtonian;

nu             nu 0 2 -1 0 0 0 0 0.01;     // l0^2/t0 == 1/Re
D               D 0 2 -1 0 0 0 0 1e-5;     // l0^2/t0 == 1/Pe
lR             lR 0 1  0 0 0 0 0 0.02;     // Reactive length D/(k*l0)

// ************************************************************************* //
[/CODE
Here is the fvSolution
PHP Code:
[CODE]
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    
version     2.0;
    
format      ascii;
    class       
dictionary;
    
location    "system";
    
object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    
p
    
{
        
solver                  GAMG;
        
smoother                GaussSeidel;
        
cacheAgglomeration      true;
        
nCellsInCoarsestLevel   10;
        
agglomerator            faceAreaPair;
        
mergeLevels             1;
        
tolerance               1e-9;
        
relTol                  4e-1;
    }

    
Urel
    
{

        
solver                  smoothSolver;
        
smoother                GaussSeidel;
        
tolerance               1e-9;
        
relTol                     0.4;
        
nSweeps               10;
    }

    
C
    
{
        
solver                  GAMG;
        
smoother                GaussSeidel;
        
agglomerator            faceAreaPair;
        
nCellsInCoarsestLevel   10;
        
mergeLevels             1;
        
tolerance               1e-9;
        
relTol                  1e-9;
    }

}

SIMPLE
{
    
nNonOrthogonalCorrectors  1;
    
consistent              yes;
    
pRefCell                  0;
    
pRefValue                 0;

    
residualControl
    
{
        
p                  1e-6;
        
Urel               1e-6;
    }
}

relaxationFactors
{
    
fields
    
{
        
p                  0.9;
    }
    
equations
    
{
        
Urel               0.6;
        
C                  1.0;
    }
}

convDiff
{
    
tolerance              1e-6;
    
maxIter                100;
}

// ************************************************************************* //
                                                                                                                                                                            
82,8          Bot
[/CODE
Can anyone give some idea about why the pressure won't converge?
Many thanks in advance!!

Ziyao
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