| sc.park |
February 8, 2016 15:46 |
SHM problem : KVLCC2 with appendage mesh
5 Attachment(s)
Hi all,
I'm trying to make a mesh for KVLCC2 (an oil tanker) with its appendage(ESD, Energy Saving Device). I made an .stl file of KVLCC2 & appendage (semicircular duct) with Gridgen, and trying to make a mesh using SHM(SnappyHexMesh).
However, I cannot make fine mesh for appendage. I refined KVLCC2 hull for level 6, and made two searchable boxes for AP, FP and refined level 7, 6 for each. And, made two more searchable box for ESD zone 1&2, and refined level 8, 9 for each. Finally I refined ESD for level 11.
I changed refine level of ESD zone 1&2, and ESD itself, but it doesn't make it. Intersection of hull(stern place) and ESD always have dirty surface.
If anybody know directions to develope this mesh, please help me.
I attached some image files, SHM code of my mesh.
thanks.
(Sorry for my poor English, I'm not native speaker T.T)
SHM dict code :
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Which of the steps to run
castellatedMesh true;
snap true;
addLayers true;
// Geometry. Definition of all surfaces. All surfaces are of class
// searchableSurface.
// Surfaces are used
// - to specify refinement for any mesh cell intersecting it
// - to specify refinement for any mesh cell inside/outside/near
// - to 'snap' the mesh boundary to the surface
geometry
{
hull.stl
{
type triSurfaceMesh;
name hull;
patchInfo
{
type wall;
}
}
ESD.stl
{
type triSurfaceMesh;
name hull;
patchInfo
{
type wall;
}
}
/*hull_top.stl
{
type triSurfaceMesh;
name hull_top;
patchInfo
{
type wall;
}
}*/
Box
{
type searchableBox;
min (-1.48 -0.1 -1.4);
max (8.312 2 1);
}
FP
{
type searchableBox;
min (-0.25 -0.1 -0.26);
max (0.36 0.5 1);
}
AP
{
type searchableBox;
min (5.13 -0.1 -0.26);
max (5.73 0.5 1);
}
ESD_zone1
{
type searchableBox;
min (5.24 -0.1 -0.01);
max (5.49 0.5 0.24); //5.49 0.5 0.26
}
ESD_zone2
{
type searchableBox;
min (5.31 -0.1 0.05);
max (5.44 0.5 0.19); // 5.44 0.5 0.215
}
};
// Settings for the castellatedMesh generation.
castellatedMeshControls
{
// Refinement parameters
// ~~~~~~~~~~~~~~~~~~~~~
// If local number of cells is >= maxLocalCells on any processor
// switches from from refinement followed by balancing
// (current method) to (weighted) balancing before refinement.
maxLocalCells 2000000;
// Overall cell limit (approximately). Refinement will stop immediately
// upon reaching this number so a refinement level might not complete.
// Note that this is the number of cells before removing the part which
// is not 'visible' from the keepPoint. The final number of cells might
// actually be a lot less.
maxGlobalCells 2000000;
// The surface refinement loop might spend lots of iterations refining just a
// few cells. This setting will cause refinement to stop if <= minimumRefine
// are selected for refinement. Note: it will at least do one iteration
// (unless the number of cells to refine is 0)
minRefinementCells 1;
// Number of buffer layers between different levels.
// 1 means normal 2:1 refinement restriction, larger means slower
// refinement.
nCellsBetweenLevels 3;//1
// Explicit feature edge refinement
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Specifies a level for any cell intersected by its edges.
// This is a featureEdgeMesh, read from constant/triSurface for now.
features
(
{
file "hull.eMesh";
level 6;
}
{
file "ESD.eMesh";
level 11;
}
/*{
file "hull_top.eMesh";
level 2;
}*/
);
// Surface based refinement
// ~~~~~~~~~~~~~~~~~~~~~~~~
// Specifies two levels for every surface. The first is the minimum level,
// every cell intersecting a surface gets refined up to the minimum level.
// The second level is the maximum level. Cells that 'see' multiple
// intersections where the intersections make an
// angle > resolveFeatureAngle get refined up to the maximum level.
refinementSurfaces
{
hull
{
// Surface-wise min and max refinement level
level (6 6);
}
ESD
{
// Surface-wise min and max refinement level
level (11 11);
}/*
hull_top
{
level (1 1);
}*/
}
resolveFeatureAngle 30; //25
// Region-wise refinement
// ~~~~~~~~~~~~~~~~~~~~~~
// Specifies refinement level for cells in relation to a surface. One of
// three modes
// - distance. 'levels' specifies per distance to the surface the
// wanted refinement level. The distances need to be specified in
// descending order.
// - inside. 'levels' is only one entry and only the level is used. All
// cells inside the surface get refined up to the level. The surface
// needs to be closed for this to be possible.
// - outside. Same but cells outside.
refinementRegions
{
Box
{
mode inside;
levels ((1E15 3));
}
FP
{
mode inside;
levels ((1E15 6));
}
AP
{
mode inside;
levels ((1E15 6));
}
ESD_zone1
{
mode inside;
levels ((1E15 8));//7
}
ESD_zone2
{
mode inside;
levels ((1E15 9));//8
}
}
// Mesh selection
// ~~~~~~~~~~~~~~
// After refinement patches get added for all refinementSurfaces and
// all cells intersecting the surfaces get put into these patches. The
// section reachable from the locationInMesh is kept.
// NOTE: This point should never be on a face, always inside a cell, even
// after refinement.
locationInMesh (-4 1 0);
// Whether any faceZones (as specified in the refinementSurfaces)
// are only on the boundary of corresponding cellZones or also allow
// free-standing zone faces. Not used if there are no faceZones.
allowFreeStandingZoneFaces true;
}
// Settings for the snapping.
snapControls
{
//- Number of patch smoothing iterations before finding correspondence
// to surface
nSmoothPatch 3;
//- Relative distance for points to be attracted by surface feature point
// or edge. True distance is this factor times local
// maximum edge length.
// tolerance 4.0;
tolerance 4.0; //4
//- Number of mesh displacement relaxation iterations.
nSolveIter 100;
//- Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
nFeatureSnapIter 10;
}
// Settings for the layer addition.
addLayersControls
{
// Are the thickness parameters below relative to the undistorted
// size of the refined cell outside layer (true) or absolute sizes (false).
relativeSizes true;
// Per final patch (so not geometry!) the layer information
layers
{
hull
{
nSurfaceLayers 2;
}
ESD
{
nSurfaceLayers 2;
}
/*hull_top
{
nSurfaceLayers 3;
}*/
}
// Expansion factor for layer mesh
expansionRatio 1.4; //1.5
// Wanted thickness of final added cell layer. If multiple layers
// is the thickness of the layer furthest away from the wall.
// Relative to undistorted size of cell outside layer.
// See relativeSizes parameter.
finalLayerThickness 0.6;//0.7
// Minimum thickness of cell layer. If for any reason layer
// cannot be above minThickness do not add layer.
// See relativeSizes parameter.
minThickness 0.2; //0.3
// If points get not extruded do nGrow layers of connected faces that are
// also not grown. This helps convergence of the layer addition process
// close to features.
// Note: changed(corrected) w.r.t 17x! (didn't do anything in 17x)
nGrow 0;//0
// Advanced settings
// When not to extrude surface. 0 is flat surface, 90 is when two faces
// are perpendicular
featureAngle 130;
// Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
// Number of smoothing iterations of surface normals
nSmoothSurfaceNormals 1;
// Number of smoothing iterations of interigor mesh movement direction
nSmoothNormals 3;
// Smooth layer thickness over surface patches
nSmoothThickness 10;
// Stop layer growth on highly warped cells
maxFaceThicknessRatio 0.5;
// Reduce layer growth where ratio thickness to medial
// distance is large
maxThicknessToMedialRatio 0.3;
// Angle used to pick up medial axis points
// Note: changed(corrected) w.r.t 17x! 90 degrees corresponds to 130 in 17x.
minMedianAxisAngle 90;
// Create buffer region for new layer terminations
nBufferCellsNoExtrude 3;
// Overall max number of layer addition iterations. The mesher will exit
// if it reaches this number of iterations; possibly with an illegal
// mesh.
nLayerIter 100;
// Max number of iterations after which relaxed meshQuality controls
// get used. Up to nRelaxIter it uses the settings in meshQualityControls,
// after nRelaxIter it uses the values in meshQualityControls::relaxed.
nRelaxedIter 30;
}
// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
#include "meshQualityDict"
}
// Advanced
// Flags for optional output
// 0 : only write final meshes
// 1 : write intermediate meshes
// 2 : write volScalarField with cellLevel for postprocessing
// 4 : write current intersections as .obj files
debug 0;
// Merge tolerance. Is fraction of overall bounding box of initial mesh.
// Note: the write tolerance needs to be higher than this.
mergeTolerance 1E-6;
// ************************************************************************* //
SurfaceFeature Extract code :
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object surfaceFeatureExtractDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
hull.stl
{
// How to obtain raw features (extractFromFile || extractFromSurface)
extractionMethod extractFromSurface;
extractFromSurfaceCoeffs
{
// Mark edges whose adjacent surface normals are at an angle less
// than includedAngle as features
// - 0 : selects no edges
// - 180: selects all edges
includedAngle 180; //150
}
subsetFeatures
{
// Keep nonManifold edges (edges with >2 connected faces)
nonManifoldEdges yes;
// Keep open edges (edges with 1 connected face)
openEdges yes;
}
// Write options
// Write features to obj format for postprocessing
writeObj yes;
}
ESD.stl
{
// How to obtain raw features (extractFromFile || extractFromSurface)
extractionMethod extractFromSurface;
extractFromSurfaceCoeffs
{
// Mark edges whose adjacent surface normals are at an angle less
// than includedAngle as features
// - 0 : selects no edges
// - 180: selects all edges
includedAngle 180; //150
}
subsetFeatures
{
// Keep nonManifold edges (edges with >2 connected faces)
nonManifoldEdges yes;
// Keep open edges (edges with 1 connected face)
openEdges yes;
}
// Write options
// Write features to obj format for postprocessing
writeObj yes;
}
/*hull_top.stl
{
extractionMethod extractFromSurface;
extractFromSurfaceCoeffs
{
includedAngle 180;
}
subsetFeatures
{
nonManifoldEdges yes;
openEdges yes;
}
writeObj yes;
}
*/
// ************************************************************************* //
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