[chayoun]

Hello everyone,


I have troubles to add extra cell layers at the bottom of my mesh like Scott A.Brown (2016) did in his PhD. I want to add 6 cell layers at the bottom of my mesh, each layer being twice thicker than the layer below it. The smallest one at the bottom should be 1mm thick.


Using tutorials, forum posts and youtube videos, I end up with those parameters to add the layers.

addLayersControls
 {
     layers
     {
        bottom
        {
           nSurfaceLayers 6;
        }
     }
      
     

   relativeSizes false;
    expansionRatio 2.0;
    firstLayerThickness 1e-3;
    minThickness 5e-1;
    nGrow 2;
 
 
     // Advanced settings
  
 
     // Static analysis of starting mesh
 
 
     featureAngle 130;
     layerTerminationAngle -180;
     maxFaceThicknessRatio 0.5;
 
 
     // Patch displacement
 
 
     nSmoothSurfaceNormals 3;
     nSmoothThickness 10;
 
 
     // Medial axis analysis
      
    

   minMedialAxisAngle 90;
    maxThicknessToMedialRatio 0.3;
    nSmoothNormals 3;
 
 
     // Mesh shrinking
 
 
     slipFeatureAngle 30;
     nRelaxIter 5;
 
 
     nBufferCellsNoExtrude 0;
     nLayerIter 50;
 
 
 }

No layers are added at the bottom patch of the mesh.



Looking at the polyMesh directory and its set sub-directory, the files « addedCells » and « layerFaces » are empty but the other files « nonAlignFaces », « nonOrthoFaces », « skewFaces » and « wrongFaces » are not.


I have been struggling for months with it, using documentation, forum and even youtube videos to help me but I am obviously missing something important here.



Any help would be more than welcome !


Please find attached my case, run it with the Allrun script attached.


Best regards,


Clarisse Hayoun

p { margin-bottom: 0.25cm; line-height: 115%; background: transparent }

[AtoHM]

You might missed there is a switch at the top of the snappyHexMeshDict. You have to enable addLayers there for snappy to perform that phase of meshing.

I hope it's just that, can't see any obvious error in the rest there.

[chayoun]

Originally Posted by AtoHM

You might missed there is a switch at the top of the snappyHexMeshDict. You have to enable addLayers there for snappy to perform that phase of meshing.

I hope it's just that, can't see any obvious error in the rest there.

Thank you for your reply AtoHM.


I did run it with the switch on, in the dict that I shared with you it might not be on as I tried the other steps before hand to be sure you could run it fully.


Best,


Clarisse

[AtoHM]

Ok, I checked the case just now.
You reference a region called "frontBack" in the layers-subdictionary. But this name is not declared anywhere in the geometry-section, so it is just ignored.

[chayoun]

Originally Posted by AtoHM

Ok, I checked the case just now.
You reference a region called "frontBack" in the layers-subdictionary. But this name is not declared anywhere in the geometry-section, so it is just ignored.

The patch "frontBack" belongs to the blockMeshDict. How do I put this in the geometry-section of snappy?

[AtoHM]

Oh that seems right. Unfortunately, I never used it that way and I found someone else had a similar issue unanswered: Why doesn't SnappyHexMesh retain patches from BlockMesh


Maybe someone else knows how to add layers to a patch from blockMesh?