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change of mesh causing continuity error in interFOAM

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Old   July 2, 2017, 07:10
Default change of mesh causing continuity error in interFOAM
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Ashok
Join Date: Feb 2017
Posts: 31
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Hello,

I have created a Case with blockMesh divisions (x y z)=(20 20 50). Now I have just changed the mesh divisions to (10 10 30) and rest all were left undisturbed includind BC's, fvschemes, fvsolutions etc. When I ran interFoam in the first case with blockMesh (20 20 50) interFOAM works fine but in the second case (10 10 30) it leads to an error as below,

The Geometry is a Cylinder with sidewall-moving.

--> FOAM FATAL ERROR:
Continuity error cannot be removed by adjusting the outflow.
Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.
Total flux : 1e-300
Specified mass inflow : 1.18713e-19
Specified mass outflow : 1.29505e-19
Adjustable mass outflow : 0

I am surprised, why does change of mesh cause such error. In my idea i strongly believe that wrong BC's leads to such error.

Can anyone help me to rectify this problem.(blockMesh, BC's for p_rhg and u are as below)

BlockmeshDict (fine)
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 4.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 1.0;

vertices
(
( 0.0315 0.0 0.0315)
(-0.0315 0.0 0.0315)
(-0.0315 0.0 -0.0315)
( 0.0315 0.0 -0.0315)
( 0.0445477272547318 0.0 0.0445477271747732)
(-0.0445477272547318 0.0 0.0445477271747732)
(-0.0445477272547318 0.0 -0.0445477271747732)
( 0.0445477272547318 0.0 -0.0445477271747732)
( 0.0315 0.5 0.0315)
(-0.0315 0.5 0.0315)
(-0.0315 0.5 -0.0315)
( 0.0315 0.5 -0.0315)
( 0.0445477272547318 0.5 0.0445477271747732)
(-0.0445477272547318 0.5 0.0445477271747732)
(-0.0445477272547318 0.5 -0.0445477271747732)
( 0.0445477272547318 0.5 -0.0445477271747732)

);

blocks
(
hex (1 0 3 2 9 8 11 10) (20 20 50) simpleGrading (1 1 1)
hex (5 4 0 1 13 12 8 9) (20 20 50) simpleGrading (1 5 1)
hex (1 2 6 5 9 10 14 13) (20 20 50) simpleGrading (1 0.2 1)
hex (2 3 7 6 10 11 15 14) (20 20 50) simpleGrading (1 0.2 1)
hex (3 0 4 7 11 8 12 15 ) (20 20 50) simpleGrading (1 0.2 1)
);


edges
(
arc 4 5 (0.0 0.0 0.063)
arc 5 6 (-0.063 0.0 0.0)
arc 6 7 (0.0 0.0 -0.063)
arc 7 4 (0.063 0.0 0.0)
arc 12 13 (0.0 0.5 0.063)
arc 13 14 (-0.063 0.5 0.0)
arc 14 15 (0.0 0.5 -0.063)
arc 15 12 (0.063 0.5 0.0)

);

boundary
(
movingWall
{
type wall;
faces
(
(5 4 12 13)
(5 13 14 6)
(6 14 15 7)
(7 15 12 4)
);
}

atmosphere
{
type patch;
faces
(
(8 11 10 9)
(8 12 15 11)
(12 8 9 13)
(9 10 14 13)
(11 15 14 10)
);
}
bottomWall
{
type patch;
faces
(
(0 3 2 1)
(0 4 7 3)
(4 0 1 5)
(1 2 6 5)
(3 7 6 2)
);
}
);

mergePatchPairs
(
);

// ************************************************** *********************** //

p_rgh

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 4.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform 0;

boundaryField
{
movingWall
{
type zeroGradient;
//p0 uniform 0;
}

atmosphere
{
type zeroGradient;
}

bottomWall
{
type zeroGradient;
}


}

// ************************************************** *********************** //

U

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 4.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
location "0";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField uniform (0 0 0);

boundaryField
{
movingWall
{
type fixedValue;
value uniform (0 -0.4247 0);
}

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

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

}


// ************************************************** *********************** //
Attached Images
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