OpenFOAM calculation mesh artefacts.

Is anyoune, who works with OpenFOAM knows how to remove such artefacts form smooth surface. They appear adter prepating calculation mesh.

 

Hi Alexanov, could you post your mesh settings? I assume you created the mesh using snappy?

 

FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}

castellatedMesh true;
snap false;
addLayers false;
mergeTolerance 1e-6;

geometry
{
hull
{
type triSurfaceMesh;
file "hull.stl";
}
}

castellatedMeshControls
{
maxLocalCells 1000000;
maxGlobalCells 2000000;
minRefinementCells 10;
nCellsBetweenLevels 2;
resolveFeatureAngle 30;

refinementSurfaces
{
hull
{
level (4 5);
patchInfo
{
type wall;
}
}
}

locationInMesh (4 0.5 -0.5);
allowFreeStandingZoneFaces false;
}

snapControls
{
nSmoothPatch 3;
tolerance 1.0;
nSolveIter 30;
nRelaxIter 5;
}

meshQualityControls
{
maxNonOrtho 65;
maxBoundarySkewness 20;
maxInternalSkewness 4;
maxConcave 80;
minTetQuality 1e-30;
minVol 1e-13;
minVolRatio 0.01;
minArea -1;
minTwist 0.02;
minDeterminant 0.001;
minFaceWeight 0.05;
nSmoothScale 4;
errorReduction 0.75;
}

 

Hi Alexander!

I see that you have value "false" for "snap" so your snappyHexMesh is executing only castellatedMesh. Your hull is made only by splitting and removing blocks from the domain. If you want a smooth shape of the hull you should set "snap" to "true".

 

Didn't have the time to take a look but I assume Alexanov set snap and addLayers to false for debugging/ step-by -step meshing. Otherwise we wouldn't see the hull at all @Night Sky Yachts

 

Ok, that makes sense. I didn't look at the picture in detail.
Probably, the problem is in the base size of cells in the domain or in snapControls.
I usually use a lot more iterations in "snap" step.
My typical settings for the hull below:

snapControls
{
nSmoothPatch 4;
tolerance 2;
nSolveIter 150;
nRelaxIter 15;
nFeatureSnapIter 50;
implicitFeatureSnap false;
explicitFeatureSnap true;
multiRegionFeatureSnap false;
}