[Bob Tipton]

I had been successfully running a large number of analyses using a combination of openFOAM and SimFlow.

The purpose of my research is to maximize the drag coefficient on a sail like device and I was close to the culminating analysis for a paper. When I took all of the early research from the project and incorporated it into a new design - the CFD analysis diverged badly. This has been the case throughout the project because the entire goal is to maximize a vortex.

After making some changes to the default settings of SimFlow (which may have modified the default settings for openFOAM?) I can no longer successfully mesh anything. As I was experimenting with changing the settings I failed to make note of the original values and now I cannot go back.

As of this point SnappyHexMesh is badly broken - either running through SimFlow or through the command line.

It seems my best course of action is a full reset to the original conditions.

The problem is in the snapping phase. The mesh divides well and boundary layers are applied, but the resulting mesh is very finely castellated - not smooth to the model.

I'm running on Win-10 using Windows Subsystem for Linux. Simflow is running directly under windows but I'm running the analyses from a WSL console window. The only hardware I have access too is a mid range HP laptop with 8 GB of RAM. It is very under powered for this task, but it's been getting the job done up until now.

FYI this is an unfunded, under resourced effort so I don't have access to large computational resources.

[Bob Tipton]

I was able to mesh in SimFlow again.
However I need access to more features than SimFlow can provide. When I try to run the same case from the command line using snappyHexMesh I get results like the attached one.

I recall that I had been able to run blockMesh and snappyHexMesh on the output from SimFlow - but when I do that now I get the attached image.

My sequence of calls is

surfaceFeatureExtract
blockMesh
snappyHexMesh

I have also run blockMesh before surfaceFeatureExtract but from my understanding they are order independent.

FoamFile
{
version 2.0;
class dictionary;
format ascii;
location "system";
object blockMeshDict;
}
convertToMeters 1;
edges
(
);
vertices
(
(-5.0 0.0 0.0)
(15.0 0.0 0.0)
(15.0 10.0 0.0)
(-5.0 10.0 0.0)
(-5.0 0.0 10.0)
(15.0 0.0 10.0)
(15.0 10.0 10.0)
(-5.0 10.0 10.0)
);
blocks
(
hex (0 1 2 3 4 5 6 7) (40 20 20) simpleGrading (1.0 1.0 1.0)
);
boundary
(
boundaries
{
type patch;
faces
(
(2 6 5 1)
(3 7 6 2)
(4 5 6 7)
(0 4 7 3)
);
}

symmetry
{
type symmetry;
faces
(
(1 5 4 0)
(0 3 2 1)
);
}

);

FoamFile
{
version 2.0;
class dictionary;
format ascii;
location "system";
object snappyHexMeshDict;
}
castellatedMesh true;
snap true;
addLayers true;
geometry
{
Inner.stl
{
type triSurfaceMesh;
simflowType stl;
name Inner;
includedAngle 120.0;
}
Mid.stl
{
type triSurfaceMesh;
simflowType stl;
name Mid;
includedAngle 120.0;
}
Outer.stl
{
type triSurfaceMesh;
simflowType stl;
name Outer;
includedAngle 120.0;
}
Refinement.stl
{
type triSurfaceMesh;
simflowType stl;
name Refinement;
includedAngle 120.0;
}
}
castellatedMeshControls
{
locationInMesh (3.3 2.45 2.6);
refinementSurfaces
{
Inner
{
level ( 4 4 );
patchInfo
{
type wall;
}
}
Mid
{
level ( 5 5 );
patchInfo
{
type wall;
}
}
Outer
{
level ( 5 5 );
patchInfo
{
type wall;
}
}
}
refinementRegions
{
Refinement
{
mode inside;
levels ((1.0E30 2));
}
}
limitRegions
{
}
features
(
{
file "Inner.eMesh";
levels ((0 0));
}
{
file "Mid.eMesh";
levels ((0 0));
}
{
file "Outer.eMesh";
levels ((0 0));
}
);
maxLocalCells 500000;
maxGlobalCells 4000000;
nCellsBetweenLevels 4;
maxLoadUnbalance 0.1;
minRefinementCells 10;
resolveFeatureAngle 30.0;
allowFreeStandingZoneFaces true;
}
snapControls
{
tolerance 1.0;
nSmoothPatch 3;
nSolveIter 500;
nRelaxIter 5;
nFeatureSnapIter 10;
implicitFeatureSnap true;
explicitFeatureSnap true;
multiRegionFeatureSnap true;
nFaceSplitInterval 5;
}
addLayersControls
{
layers
{
Inner
{
nSurfaceLayers 5;
expansionRatio 1.15;
firstLayerThickness 0.1;
}
Inner_patch0
{
nSurfaceLayers 5;
expansionRatio 1.15;
firstLayerThickness 0.1;
}
Mid
{
nSurfaceLayers 5;
expansionRatio 1.15;
firstLayerThickness 0.1;
}
Mid_patch0
{
nSurfaceLayers 5;
expansionRatio 1.15;
firstLayerThickness 0.1;
}
Outer
{
nSurfaceLayers 5;
expansionRatio 1.15;
firstLayerThickness 0.1;
}
Outer_patch0
{
nSurfaceLayers 5;
expansionRatio 1.15;
firstLayerThickness 0.1;
}
}
relativeSizes true;
minThickness 0.001;
firstLayerThickness 1.0E-4;
expansionRatio 1.25;
nGrow 0;
featureAngle 180.0;
maxFaceThicknessRatio 0.5;
nSmoothSurfaceNormals 5;
nSmoothThickness 10;
minMedialAxisAngle 90.0;
maxThicknessToMedialRatio 0.5;
nMedialAxisIter 100;
nSmoothNormals 3;
slipFeatureAngle 30.0;
nRelaxIter 5;
nBufferCellsNoExtrude 0;
nLayerIter 50;
nRelaxedIter 20;
detectExtrusionIsland true;
}
meshQualityControls
{
maxNonOrtho 65.0;
maxBoundarySkewness 20.0;
maxInternalSkewness 4.0;
maxConcave 80.0;
minVol 1.0E-14;
minTetQuality 1.0E-20;
minArea -1.0;
minTwist 0.02;
minTriangleTwist -1.0;
minDeterminant 0.01;
minFaceWeight 0.05;
minVolRatio 0.01;
minVolCollapseRatio 0.1;
nSmoothScale 4;
errorReduction 0.75;
relaxed
{
maxNonOrtho 75.0;
}
}
mergeTolerance 1.0E-6;
debug 0;