|July 27, 2012, 07:00||
simpleFoam for complicated geometry, non-orthogonal mesh, omega wall function
Join Date: May 2010
Posts: 66Rep Power: 5
I am using simpleFoam on complicated geometry (non orthogonal mesh). Here is the checkMesh report:
internal faces: 18938278
boundary patches: 16
point zones: 0
face zones: 0
cell zones: 0
Overall number of cells of each type:
tet wedges: 0
Boundary definition OK.
Cell to face addressing OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (9.64958e-17 2.34786e-15 -6.13025e-16) OK.
Max cell openness = 4.58304e-15 OK.
Max aspect ratio = 299.485 OK.
Minumum face area = 3.41806e-11. Maximum face area = 0.000249108. Face area magnitudes OK.
Min volume = 1.22828e-14. Max volume = 4.16394e-07. Total volume = 0.20005. Cell volumes OK.
Mesh non-orthogonality Max: 87.0638 average: 19.2898
*Number of severely non-orthogonal faces: 18931.
Non-orthogonality check OK.
<<Writing 18931 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
Max skewness = 2.88371 OK.
Coupled point location match (average 0) OK.
I am using SST turbulence model. I am using 'flowRateInletVelocity' for few inlets and it's mentioned like this:
flowRate constant XXXX; // volume flow rate
value uniform (0 0 0);
The boundary conditions for k and omega are:
Feature k, omega
Turbulent inlet 0.4, 4000
Other inlets 1e-6, 1e-2
Walls type kqRWallFunction; type omegaWallFunction;
value uniform 0.4; value uniform 4000;
Outlet zeroGradient, zeroGradient
internal field 0.4, 4000
I am using DICPCG for pressure, smoothSolver for omega and DILUPBiCG for others.
My fvSchemes were as follows:
default Gauss linear;
div(phi,U) Gauss linearUpwindV grad(U);
div(phi,k) Gauss upwind;
div(phi,omega) Gauss upwind;
div((nuEff*dev(T(grad(U))))) Gauss linear;
default Gauss linear corrected;
The simulation diverges after 150 steps. I tried Gauss linear limited 0.333 for laplacian schemes which didn't work. gradSchemes was changed to 'cellLimited Gauss linear 1' and it was not good either.
Could someone give me tips to improve the simulation?
Note: When i use epsilonWallFunction(as wall boundary condition) for omega, it converges to some decent results (not accurate though) with the 1st set of fvSchemes. It's strange!!
Last edited by achinta; July 27, 2012 at 07:07. Reason: typos
|October 20, 2013, 10:22||
how did u determine k and omega for complicated geometry
Join Date: Dec 2011
Location: Cranfield, United Kingdom
Posts: 69Rep Power: 3
I am stuck with similar problem but I'm a one step before u
How did u determine the K and Omega for the complicated geometry, and did u over come the problem ? i am having the same problem
|October 25, 2013, 01:58||
k and omega
B T KANNAN
Join Date: Jul 2011
Location: CHENNAI (MADRAS), INDIA
Posts: 45Rep Power: 4
Try to calculate k and epsilon from the intensity and velocity, which you know for inlet. If not, get it from experiments(available in literature). Then calculate omega by omega=epsilon/k
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