CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Meshing & Mesh Conversion > OpenFOAM Native Meshers: snappyHexMesh and Others

bumps and broken surface after meshing with snappyhexmesh

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   February 12, 2018, 13:07
Default bumps and broken surface after meshing with snappyhexmesh
  #1
New Member
 
Richard adeyemi
Join Date: Apr 2012
Posts: 2
Rep Power: 0
Yemi2favours is on a distinguished road
Dear all,


I would like to count on your expertise and wealth of experiences. Am trying to create a mesh in OpenFoam using SHMdict. i have done some preliminary works and meshing. Please see the attached my dict, geometry and meshing figures. I could observed that after snappyhexmesh is applied, there is broken surface on my blades.
How can i correct this error?


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 3.0.1 |
| \\ / 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;// was set true before
snap true;
addLayers false;// was set false before

// set addLayers at first. you can always go back and change to true when there is no more error.
// 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
{
//outercube.stl {type triSurfaceMesh; name outercube;}
//innercube.stl {type triSurfaceMesh; name innercube;}
//innercylindersmal1.stl {type triSurfaceMesh; name innercylindersmal1;}
//blades.stl {type triSurfaceMesh; name blades;}

outercube.stl
{
type triSurfaceMesh;
name outercube;
}

innercube.stl
{
type triSurfaceMesh;
name innercube;
}

innercylindersmal1.stl
{
type triSurfaceMesh;
name innercylindersmal1;
}

blades.stl
{
type triSurfaceMesh;
name blades;
}
/* outercube.stl
{
type triSurfaceMesh;
name outercube;
regions
{
outercube
{
name outercube;
}
}
}

innercube.stl
{
type triSurfaceMesh;
name innercube;
regions
{
innercube
{
name innercube;
}
}
}
innercylindersmal1.stl
{
type triSurfaceMesh;
name innercylindersmal1;
regions
{
innercylindersmal1
{
name innercylindersmal1;

}
}
}

blades.stl
{
type triSurfaceMesh;
name blades;
regions
{
blades
{
name blades;
}
}
}
*/ //refinementBox {type searchableBox; min (-25 -30.2509 -20.9932); max ( 30 30.129 24.0068);
};

// Settings for the castellatedMesh generation.

castellatedMeshControls
{

maxLocalCells 1000000;
maxGlobalCells 20000000;
minRefinementCells 0;// was 100
maxLoadUnbalance 0.10;
nCellsBetweenLevels 3; // it was 7 before.

// Explicit feature edge refinement
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

features // taken from STL from each .eMesh file created by "SurfaceFeatureExtract" command
(
{
file "innercylindersmal1.eMesh";
level 2; //was 3
}
{
file "outercube.eMesh";
level 0;
}
{
file "blades.eMesh";
level 3; // was 4
}
{
file "innercube.eMesh";
level 1; // was 2
}

);

// Surface based refinement
// ~~~~~~~~~~~~~~~~~~~~~~~

refinementSurfaces
{
innercylindersmal1
{
level (2 2); // was (3 3) before

faceType boundary;
cellZone innercylindersmal1;
faceZone innercylindersmal1;
cellZoneInside inside;
}
outercube
{
level (0 0);// it was initially (0 0)
}
blades
{
level (3 3);// was initially (4,4)
}
//innercube
//{
// level (3 3);// it was (4 4) and was commented
//}

}


resolveFeatureAngle 30; // it can use 95

// Region-wise refinement
// ~~~~~~~~~~~~~~~~~~~~~~

refinementRegions
{
// innercube
//{
// mode inside;
//levels ((1E15 3));// it was 3 before and commented
// }
innercylindersmal1
{
mode inside;
levels ((1E15 2)); // it was 3
}

}

// Mesh selection
// ~~~~~~~~~~~~~~
locationInMesh (8.2 12.906 9.16859); // it was (-0.153401 0.15340 0.450484)
allowFreeStandingZoneFaces true;
}

// Settings for the snapping.
snapControls
{

nSmoothPatch 4;// was 3 before
tolerance 1.0; // was 4.0;
nSolveIter 300; // was 30 before
nRelaxIter 5; // it was 10 before

// Feature snapping
nFeatureSnapIter 15; // was 10 before
implicitFeatureSnap false;
explicitFeatureSnap true;
multiRegionFeatureSnap false; //it was true before. Just for explicit method, "...detect features between multiple surfaces..."
}

// Settings for the layer addition.
addLayersControls
{

relativeSizes true;// was false before
layers

{
blades
{
nSurfaceLayers 3; // was commented and set to 5.
}

}

// Expansion factor for layer mesh
expansionRatio 1.2;// was 1.0
finalLayerThickness 0.1;// was 0.16
minThickness 0.01;// was 0.08
nGrow 0; // was 1

// Advanced settings
featureAngle 60; //it was 30 before. i can use 60 as well
nRelaxIter 20;// was 3
nSmoothSurfaceNormals 1;
nSmoothNormals 3;
nSmoothThickness 10;
maxFaceThicknessRatio 0.5;
maxThicknessToMedialRatio 0.3; // it was 0.3 before
minMedianAxisAngle 130;
nBufferCellsNoExtrude 0;
nLayerIter 100; // was 50.
slipFeatureAngle 30;
}

// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
// Specify mesh quality constraints in separate dictionary so can
// be reused (e.g. checkMesh -meshQuality)
#include "meshQualityDict"
relaxed
{

maxNonOrtho 75;
}


// Advanced
nSmoothScale 4;
errorReduction 0.75;
}
// Advanced
// put 1 if you wnat to write all the meshes at each stage so that you look and make correction and 0 if not
debug 0; //0: only write final meshes

// Merge tolerance. Is fraction of overall bounding box of initial mesh.
// Note: the write tolerance needs to be higher than this.
mergeTolerance 1e-6;


// ************************************************** *********************** //
Attached Images
File Type: jpg bladepic3..jpg (39.6 KB, 11 views)
File Type: jpg presentmesh.jpg (203.9 KB, 11 views)
File Type: png snapshot00.png (31.1 KB, 11 views)
File Type: png snapshot02.png (76.4 KB, 11 views)
Yemi2favours is offline   Reply With Quote

Reply

Tags
openfoam 2.1, snappyhesmeshdict, snappyhexmesh 3d

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 15:21.