| Pat84 |
August 12, 2013 09:15 |
simpleFoam kOmegaSST LowRe pressure divergence
4 Attachment(s)
Dear all,
I would like to test the kOmegaSST low reynolds turbulence model with a t-junction and have generated my mesh in icem. I´ve tested the mesh in fluent and have planned to compare the result of fluent and openfoam, but when I use the icem mesh ( I convert the .msh file with fluent3DMeshToFoam ) I get very high residuals for the pressure - in order of 0.6 - 1.0 and up to 1000 iterations. After a while the simulation diverges. I use the same BC in fluent and OF, but in fluent the simulation works - y+ max is ~0.6. I think the error lies in the conversion of the mesh from .msh to openfoam mesh, since there are two warnings while converting:
Code:
fluent3DMeshToFoam mixingtee.msh
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM Extend Project: Open source CFD |
| \\ / O peration | Version: 1.6-ext |
| \\ / A nd | Web: www.extend-project.de |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 1.6-ext-bd38c3b48291
Exec : fluent3DMeshToFoam mixingtee.msh
Date : Aug 12 2013
Time : 14:56:49
Host : Knecht.site
PID : 8419
Case : /home/patrick/OpenFOAM/patrick-1.6-ext/run/mixingtee_fineWall
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time
Dimension of grid: 3
Number of points: 399592
PointGroup: 15 start: 0 end: 399591 nComponents: 3. Reading points...done.
Number of cells: 391417
CellGroup: 16 start: 0 end: 391416 type: 1
Number of faces: 1182246
FaceGroup: 17 start: 0 end: 1166255. Reading uniform faces...done.
FaceGroup: 18 start: 1166256 end: 1168348. Reading uniform faces...done.
FaceGroup: 19 start: 1168349 end: 1170441. Reading uniform faces...done.
FaceGroup: 20 start: 1170442 end: 1172534. Reading uniform faces...done.
FaceGroup: 21 start: 1172535 end: 1182245. Reading uniform faces...done.
Zone: 16 name: FLUID type: fluid. Reading zone data...done.
Zone: 17 name: int_FLUID type: interior. Reading zone data...done.
Zone: 18 name: INLET-Y type: velocity-inlet. Reading zone data...done.
Zone: 19 name: INLET-Z type: velocity-inlet. Reading zone data...done.
Zone: 20 name: OUTLET type: outlet-vent. Reading zone data...done.
Zone: 21 name: WALL type: wall. Reading zone data...done.
FINISHED LEXING
--> FOAM Warning :
From function min(const UList<Type>&)
in file lnInclude/FieldFunctions.C at line 342
empty field, returning zero
--> FOAM Warning :
From function min(const UList<Type>&)
in file lnInclude/FieldFunctions.C at line 342
empty field, returning zero
Creating patch 0 for zone: 18 name: INLET-Y type: velocity-inlet
Creating patch 1 for zone: 19 name: INLET-Z type: velocity-inlet
Creating patch 2 for zone: 20 name: OUTLET type: outlet-vent
Creating patch 3 for zone: 21 name: WALL type: wall
Creating cellZone 0 name: FLUID type: fluid
Creating faceZone 0 name: int_FLUID type: interior
faceZone from Fluent indices: 0 to: 1166255 type: interior
patch 0 from Fluent indices: 1166256 to: 1168348 type: velocity-inlet
patch 1 from Fluent indices: 1168349 to: 1170441 type: velocity-inlet
patch 2 from Fluent indices: 1170442 to: 1172534 type: outlet-vent
patch 3 from Fluent indices: 1172535 to: 1182245 type: wall
From function void polyMesh::initMesh()
in file meshes/polyMesh/polyMeshInitMesh.C at line 82
Truncating neighbour list at 1166256 for backward compatibility
Writing mesh to "/home/patrick/OpenFOAM/patrick-1.6-ext/run/mixingtee_fineWall/constant/region0"
End
The problem is, that checkMesh returns no error, but if you have a look at the attached pichtures, the skewness is a bit small, or? :
Code:
checkMesh
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM Extend Project: Open source CFD |
| \\ / O peration | Version: 1.6-ext |
| \\ / A nd | Web: www.extend-project.de |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 1.6-ext-bd38c3b48291
Exec : checkMesh
Date : Aug 12 2013
Time : 15:01:12
Host : Knecht.site
PID : 8731
Case : /home/patrick/OpenFOAM/patrick-1.6-ext/run/mixingtee_fineWall
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time
Create polyMesh for time = 0
Time = 0
Mesh stats
all points: 399592
live points: 399592
all faces: 1182246
live faces: 1182246
internal faces: 1166256
cells: 391417
boundary patches: 4
point zones: 0
face zones: 1
cell zones: 1
Overall number of cells of each type:
hexahedra: 391417
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0
Checking topology...
Boundary definition OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).
Checking patch topology for multiply connected surfaces ...
Patch Faces Points Surface topology
INLET-Y 2093 2120 ok (non-closed singly connected)
INLET-Z 2093 2120 ok (non-closed singly connected)
OUTLET 2093 2120 ok (non-closed singly connected)
WALL 9711 9788 ok (non-closed singly connected)
Checking geometry...
This is a 3-D mesh
Overall domain bounding box (-0.0761695 -0.3556 -0.0760639) (0.0761887 0.3556 0.37465)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Mesh (non-empty, non-wedge) dimensions 3
Boundary openness (-1.40907e-15 -1.33355e-16 2.53797e-16) Threshold = 1e-06 OK.
Max cell openness = 3.84166e-14 OK.
Max aspect ratio = 813.001 OK.
Minumum face area = 1.92001e-08. Maximum face area = 8.03386e-05. Face area magnitudes OK.
Min volume = 1.01453e-10. Max volume = 2.12297e-07. Total volume = 0.0153058. Cell volumes OK.
Mesh non-orthogonality Max: 58.654 average: 15.2185 Threshold = 70
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 2.6457 OK.
Mesh OK.
End
I have also tried the same mesh with standard kOmegaSST and kEpsilon with wall functions, but all calculations show the same behavior.
The mesh is a full hexa mesh with o-grid. OF version is OF-1.6 extend.
The BC for k and Omega in the low reynolds SST case are zeroGradient.
What can be the reason for the pressure divergence?
Best regards,
Patrick |
