| Jahir |
February 22, 2024 20:35 |
Weird 90° corners after castellatedMesh
2 Attachment(s)
Hello.
This is my first post in this forum (lurking for a couple of months) and I hope it's not something trivial.
I'm working with an internal mesh using blockMesh + snappyHexMesh (I just started using sHM) and after some reading I've reached a decent mesh (at least after using castellatedMesh). What's worrying me is that there's a wierd corner on a fairly simple part of my geometry which I believe shouldn't have much problem. This is my sHMDict:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2312 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Which of the steps to run
castellatedMesh true;
snap false;
addLayers false;
// 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
{
inlet.stl
{
type triSurfaceMesh;
name inlet;
}
outlet.stl
{
type triSurfaceMesh;
name outlet;
}
atmosphere.stl
{
type triSurfaceMesh;
name atmosphere;
}
walls1.stl
{
type triSurfaceMesh;
name walls1;
}
walls2.stl
{
type triSurfaceMesh;
name walls2;
}
/*
refinementBox
{
type box;
min (-1.0 -0.7 0.0);
max ( 8.0 0.7 2.5);
}
*/
}
// 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 10000000;
// 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 20000000;
// 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 5;
// Allow a certain level of imbalance during refining
// (since balancing is quite expensive)
// Expressed as fraction of perfect balance (= overall number of cells /
// nProcs). 0=balance always.
maxLoadUnbalance 0.10;
// Number of buffer layers between different levels.
// 1 means normal 2:1 refinement restriction, larger means slower
// refinement.
nCellsBetweenLevels 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 "tanque.eMesh";
level 6;
}*/
);
// 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
{
inlet
{
// Surface-wise min and max refinement level
level (0 0);
patchInfo
{
type patch;
}
}
outlet
{
// Surface-wise min and max refinement level
level (0 0);
patchInfo
{
type patch;
}
}
atmosphere
{
// Surface-wise min and max refinement level
level (0 0);
patchInfo
{
type patch;
}
}
walls1
{
// Surface-wise min and max refinement level
level (0 0);
}
walls2
{
// Surface-wise min and max refinement level
level (1 1);
}
}
// Resolve sharp angles
resolveFeatureAngle 5;
// 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
{
/*tanque.stl
{
mode inside;
levels ((0 2));
}*/
}
// 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 (1 1 1);
// 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;
}
The boundary walls2 is the floor which is being refined nicely for most of the geometry. walls1 contain the vertical and top walls and a bottom wall that I don't need to refine. I've used (0 1) refinement for walls1 but I just need the bottom cells refined. I've also tried many different resolveFeatureAngle values with no succes.
After moving up to the next step, what would be your advice to have a nice refinement? :confused:
EDIT: Turned out to be something trivial, the gap was formed because the element size 0 was larger than the length of that part of the geometry. |
