| jrrygg |
February 15, 2013 07:08 |
AMI-interface "cuts" water jet
Hi!
I am working on simulating the flow in a Pelton bucket numerically, but I am having some trouble with the AMI-interface. I think this is related to the meshing in the AMI-patches, as they seem to not be perfectly circular as I want them to be.
I wonder if anyone has some tricks that may help me improve the representation of the flow over the interface? The AMI-patches should be circular, but how can I refine them?
My case is originally based on the propeller-tutorial, but I use the interDyMFoam-solver.
The water jet is cut in the AMI-interface:
https://dl.dropbox.com/u/2820596/mesh11-jetcut1.png
AMI1:
https://dl.dropbox.com/u/2820596/mes...tcut3-AMI1.png
AMI2:
https://dl.dropbox.com/u/2820596/mes...tcut4-AMI2.png
My snappyHexMeshDict:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.0 |
| \\ / 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; //Originally 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
{
jetinlet.obj
{
type triSurfaceMesh;
name jetinlet;
regions
{
jetinlet
{
name jetinlet;
}
}
}
jetwalls.obj
{
type triSurfaceMesh;
name jetwalls;
regions
{
jetwalls
{
name jetwalls;
}
}
}
BBC.obj
{
type triSurfaceMesh;
name BBC;
regions
{
BBC
{
name BBC;
}
}
}
MBC.obj
{
type triSurfaceMesh;
name MBC;
regions
{
MBC
{
name MBC;
}
}
}
TBC.obj
{
type triSurfaceMesh;
name TBC;
regions
{
TBC
{
name TBC;
}
}
}
statopening.obj
{
type triSurfaceMesh;
name statopening;
regions
{
statopening
{
name statopening;
}
}
}
rotif.obj
{
type triSurfaceMesh;
name rotif;
regions
{
rotif
{
name rotif;
}
}
}
rotopen.obj
{
type triSurfaceMesh;
name rotopen;
regions
{
rotopen
{
name rotopen;
}
}
}
rotsym.obj
{
type triSurfaceMesh;
name rotsym;
regions
{
rotsym
{
name rotsym;
}
}
}
statinlet.obj
{
type triSurfaceMesh;
name statinlet;
regions
{
statinlet
{
name statinlet;
}
}
}
statsym.obj
{
type triSurfaceMesh;
name statsym;
regions
{
statsym
{
name statsym;
}
}
}
};
// 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 100000;
// 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 1000000;
// 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 0;
// 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 2;
// 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 "jetinlet.eMesh";
level 3;
}
{
file "jetwalls.eMesh";
level 3;
}
{
file "statopening.eMesh";
level 1;
}
{
file "rotif.eMesh";
level 3;
}
{
file "BBC.eMesh";
level 3;
}
{
file "MBC.eMesh";
level 3;
}
{
file "TBC.eMesh";
level 3;
}
//4 nye
{
file "rotopen.eMesh";
level 1;
}
{
file "rotsym.eMesh";
level 1;
}
{
file "statinlet.eMesh";
level 1;
}
{
file "statsym.eMesh";
level 1;
}
);
// 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
{
BBC
{
level (2 3); //Originally (2 3) for all buckets
}
MBC
{
level (2 3);
}
TBC
{
level (2 3);
}
rotif
{
level (2 2);
cellZone rotif;
faceZone rotif;
cellZoneInside inside;
}
statopening
{
level (1 1);
}
jetinlet
{
level (2 3);
}
jetwalls
{
level (2 3);
}
//4 nye
rotopen
{
level (1 1);
}
rotsym
{
level (2 2);
}
statinlet
{
level (1 1);
}
statsym
{
level (2 3);
}
}
// Resolve sharp angles
resolveFeatureAngle 30;
// 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
{
/* rotif
{
mode inside;
levels ((1E15 3));
}
statinlet
{
mode inside;
levels ((1E15 0));
}
*/
MBC
{
mode distance;
levels ((0.05 5));
}
TBC
{
mode distance;
levels ((0.05 5));
}
BBC
{
mode distance;
levels ((0.05 5));
}
jetwalls
{
mode distance;
levels ((0.01 5));
}
jetinlet
{
mode distance;
levels ((0.01 5));
}
}
// 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 (21 601.1 211.1);
locationInMesh (-0.20545645 0.111378 0.202156456); //Originalt (0.37046464 0.111378 0.37046464)
// 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 5; //Originally 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; // 1.0;
//- Number of mesh displacement relaxation iterations.
nSolveIter 20;
//- Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 6; //Originally 5
//- Highly experimental and wip: number of feature edge snapping
// iterations. Leave out altogether to disable.
// Do not use here since mesh resolution too low and baffles present
nFeatureSnapIter 20;
}
// 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
{
}
// Expansion factor for layer mesh
expansionRatio 1.0;
//- 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.
// is the thickness of the layer furthest away from the wall.
// See relativeSizes parameter.
finalLayerThickness 0.3;
//- Minimum thickness of cell layer. If for any reason layer
// cannot be above minThickness do not add layer.
// Relative to undistorted size of cell outside layer.
minThickness 0.1;
//- 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;
// Advanced settings
//- When not to extrude surface. 0 is flat surface, 90 is when two faces
// make straight angle.
featureAngle 30;
//- Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 3;
// Number of smoothing iterations of surface normals
nSmoothSurfaceNormals 1;
// Number of smoothing iterations of interior 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 0;
// Overall max number of layer addition iterations. The mesher will exit
// if it reaches this number of iterations; possibly with an illegal
// mesh.
nLayerIter 50;
}
// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
//- Maximum non-orthogonality allowed. Set to 180 to disable.
maxNonOrtho 45; //Originally 65
//- Max skewness allowed. Set to <0 to disable.
maxBoundarySkewness 20;
maxInternalSkewness 4;
//- Max concaveness allowed. Is angle (in degrees) below which concavity
// is allowed. 0 is straight face, <0 would be convex face.
// Set to 180 to disable.
maxConcave 80;
//- Minimum pyramid volume. Is absolute volume of cell pyramid.
// Set to a sensible fraction of the smallest cell volume expected.
// Set to very negative number (e.g. -1E30) to disable.
minVol 1e-13;
//- Minimum quality of the tet formed by the face-centre
// and variable base point minimum decomposition triangles and
// the cell centre. This has to be a positive number for tracking
// to work. Set to very negative number (e.g. -1E30) to
// disable.
// <0 = inside out tet,
// 0 = flat tet
// 1 = regular tet
minTetQuality -1; // 1e-30;
//- Minimum face area. Set to <0 to disable.
minArea -1;
//- Minimum face twist. Set to <-1 to disable. dot product of face normal
//- and face centre triangles normal
minTwist 0.01;
//- minimum normalised cell determinant
//- 1 = hex, <= 0 = folded or flattened illegal cell
minDeterminant 0.001;
//- minFaceWeight (0 -> 0.5)
minFaceWeight 0.05;
//- minVolRatio (0 -> 1)
minVolRatio 0.01;
//must be >0 for Fluent compatibility
minTriangleTwist -1;
// Advanced
//- Number of error distribution iterations
nSmoothScale 6; //Originally 4
//- amount to scale back displacement at error points
errorReduction 0.75;
// Optional : some meshing phases allow usage of relaxed rules.
// See e.g. addLayersControls::nRelaxedIter.
relaxed
{
//- Maximum non-orthogonality allowed. Set to 180 to disable.
maxNonOrtho 45; //Originally 75
}
}
// 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;
// ************************************************************************* //
My createAMIFaces.topoSetDict:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: dev |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object topoSetDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
actions
(
{
name rotif;
type cellSet;
action new;
source cylinderToCell;
sourceInfo
{
p1 (0 0 0);
p2 (0 0.13908 0);
radius 0.3477;
}
}
{
name outerCells;
type cellSet;
action new;
source cellToCell;
sourceInfo
{
set rotif;
}
}
{
name outerCells;
type cellSet;
action invert;
}
{
name rotif;
type cellZoneSet;
action new;
source setToCellZone;
sourceInfo
{
set rotif;
}
}
{
name rotifFace;
type faceSet;
action new;
source cellToFace;
sourceInfo
{
set rotif;
option all;
}
}
{
name rotifFace;
type faceSet;
action subset;
source cellToFace;
sourceInfo
{
set outerCells;
option all;
}
}
{
name rotif;
type faceZoneSet;
action new;
source setsToFaceZone;
sourceInfo
{
faceSet rotifFace;
cellSet rotif;
}
}
);
// ************************************************************************* //
|
