[bvdrsch]

Hello Foamers,

I'm trying to perform a wind study on buildings. Therefore a build my 3D model in sketchup and converted it via blender to an .stl file. See attachement.

I'm using snappyHexMesh for the mesh. However when I use the addlayers possibility, some bulges arise on the edge of the surfaces.
I noticed some mid surface bulges as well.

Can somebody explain how this can occur or what a solution could be?

kr
Bruno

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v1806 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#includeEtc "caseDicts/mesh/generation/snappyHexMeshDict.cfg"

castellatedMesh on;
snap on;
addLayers yes;

geometry
{
cube.stl
{
type triSurfaceMesh;
name cube;
}

};

castellatedMeshControls
{
features
(
{ file "cube.eMesh"; level 0; }
);

refinementSurfaces
{
cube
{
level (2 5);
patchInfo { type wall; }
}
}

refinementRegions
{
refinementBox
{
mode inside;
levels ((1E15 2));
}
}

locationInMesh (1 1 1);
}

snapControls
{
explicitFeatureSnap true;
implicitFeatureSnap false;
}

addLayersControls
{
layers
{
cube
{
nSurfaceLayers 3;
}
}

relativeSizes true;
expansionRatio 1.3;
finalLayerThickness 0.5;
minThickness 1e-3;
}

meshQualityControls
{}

writeFlags
(
noRefinement
// scalarLevels
// layerSets
// layerFields
);

mergeTolerance 1e-6;

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

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v1806 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object surfaceFeatureExtractDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

cube.stl
{
#includeEtc "caseDicts/surface/surfaceFeatureExtractDict.cfg"
}

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

[Yann]

Hello,

It would help if you could post a screenshot showing the issue you are talking about.

Regards,
Yann

[bvdrsch]

Hello,

Thank you for your help.
These bulges on the edge are the ones I was talking about:


kr
Bruno

[Yann]

Thanks.
Try to add this parameter do you addLayersControls:

addLayersControls
{
	layers
	{
		cube
		{
			nSurfaceLayers 3;
		}
	}

	relativeSizes true;
	expansionRatio 1.3;
	finalLayerThickness 0.5;
	minThickness 1e-3;
	
	mergePatchFacesAngle 45;
}

Does it change something?
How is your layer coverage on your geometry, especially on these areas?

Regards,
Yann