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-   -   What does "realtivSizes" mean (http://www.cfd-online.com/Forums/openfoam-meshing-snappyhexmesh/79684-what-does-realtivsizes-mean.html)

raw_recruit August 31, 2010 08:05

What does "realtivSizes" mean
 
Hello everyone,

at the moment i am trying to get familiar with snappyHexMesh by meshing an airfoil.
I created the initial Mesh with blockMesh. Each cell i created in blockMesh is 0.5m x 0.5m x 0.5m .
The meshprocess didn't make any problems. But i don't understand what relativeSizes mean.

addLayersControls
{
relativeSizes true;

layers
{
"naca_tragflaeche"
{
nSurfaceLayers 10;
}
}

expansionRatio 1.5;
finalLayerThickness 0.8;
minThickness 0.02;
nGrow 1;
featureAngle 60;
nRelaxIter 5;
nSmoothSurfaceNormals 1;
nSmoothNormals 3;
nSmoothThickness 10;
maxFaceThicknessRatio 0.5;
maxThicknessToMedialRatio 0.3;
minMedianAxisAngle 130;
nBufferCellsNoExtrude 0;
nLayerIter 50;
}

I read that the thickness values are given as proportional to the undisorted cell size.
For me that means if I have an undisorted cell size of 0.5m (in each direction) that i multiply that value with my minThickness-value of 0.02. So i would have a minThickness of 0.01m. But in my mesh the first layer is a lot smaller.

If someone could explain to me what relativeSizes means that would be great.

Thanks a lot for your help

raw_recruit


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