[Tobermory]

I am finding that if I add a thick layer on one of the domain boundaries, SHM makes a real mess of the mesh at the other surfaces, as it shrinks the internal mesh to make way for the layer. In the example below, the mesh at the top of the cube is stretched horribly. Is there any way to control this better (other than to use a thinner layer)? I couldn't see anything in the snappyHexMeshDict controls ... any suggestions would be welcomed.

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

castellatedMesh true;
snap            true;
addLayers       true;

geometry { 
    domain
    {
        type triSurfaceMesh;
        file "cube.stl";
        name cubeSTL;                     // name of this surf inside SHM
        regions {
            top    { name cube_top ;}     // STL patch name and final name of the patch
            sides  { name cube_sides ;}
            bottom { name cube_bottom ;}
        }
    }
};



castellatedMeshControls  {
    maxLocalCells 1000000;            //default 100000;
    maxGlobalCells 5000000;            //default 2000000;
    minRefinementCells 10;
    maxLoadUnbalance 0.10;
    nCellsBetweenLevels 5;

    //feature edge refinement - eMesh read from constant/triSurface
    features (         
        { file "cube.eMesh"; level 1; }
    );

    //surface refinement
    refinementSurfaces {
        cubeSTL { 	level (1 1);
					regions {
						top { level (1 1);  patchinfo { type wall; } }
						sides { level (1 1);  patchinfo { type wall; } }
						bottom { level (1 1);  patchinfo { type wall; } }
					}
                }
    }
    resolveFeatureAngle 30;

    //volume refinement
    refinementRegions { 
    }
    
    //other mesh parameters
    locationInMesh (0 0 2);
    allowFreeStandingZoneFaces true;
}


snapControls {
    nSmoothPatch 3;
    tolerance 2.0;
    nSolveIter 30;
    nRelaxIter 5;
    nFeatureSnapIter 10;
    implicitFeatureSnap false;
    explicitFeatureSnap true;
    multiRegionFeatureSnap false;
}

addLayersControls {
    relativeSizes false;
    firstLayerThickness 0.02;
    thickness 0.2;
    layers {
        Zneg {nSurfaceLayers 5;}
     }

    minThickness 0.005;
    nGrow 0;
    featureAngle 160;
    slipFeatureAngle 30;
    nRelaxIter 5;
    nSmoothSurfaceNormals 1;
    nSmoothNormals 3;
    nSmoothThickness 10;
    maxFaceThicknessRatio 0.5;
    maxThicknessToMedialRatio 0.3;
    minMedianAxisAngle 90;
    nBufferCellsNoExtrude 0;
    nLayerIter 50;
    nRelaxedIter 20;
}

meshQualityControls {   #include "meshQualityDict" }
writeFlags ( scalarLevels    layerSets     layerFields );
mergeTolerance 1e-6;