[chotea]

Hello, everyone!

I am quite new to OpenFoam and have been having a really hard time with a simulation of a 3D tank with 3 impellers when using interFoam. More precisely, the problem is that the Courant number increases suddenly and the simulation stops.

Initially I thought that my mesh is the problem, but when I perform the "checkMesh -allGeometry -allTopology -writeAllFields" command it looks quite fine:
"Checking geometry...
Overall domain bounding box (-1.76084 -9.59407 -1.75941) (1.76027 0.0338586 1.75886)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (-2.30972e-15 -3.47421e-17 1.02735e-15) OK.
Max cell openness = 3.75366e-16 OK.
Max aspect ratio = 20.488 OK.
Minimum face area = 0.000160125. Maximum face area = 0.0480543. Face area magnitudes OK.
Min volume = 2.70491e-05. Max volume = 0.00213372. Total volume = 91.8957. Cell volumes OK.
Mesh non-orthogonality Max: 68.7956 average: 11.4968
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 2.99374 OK.
Coupled point location match (average 0) OK.
Face tets OK.
Min/max edge length = 0.00124611 0.339891 OK.
<<Writing 8 near (closer than 1.08385e-05 apart) points to set nearPoints
*There are 777 faces with concave angles between consecutive edges. Max concave angle = 62.9378 degrees.
<<Writing 777 faces with concave angles to set concaveFaces
Face flatness (1 = flat, 0 = butterfly) : min = 0.754877 average = 0.999371
*There are 10 faces with ratio between projected and actual area < 0.8
Minimum ratio (minimum flatness, maximum warpage) = 0.754877
<<Writing 10 warped faces to set warpedFaces
Cell determinant (wellposedness) : minimum: 0.00185793 average: 0.183088
Cell determinant check OK.
***Concave cells (using face planes) found, number of cells: 3060
<<Writing 3060 concave cells to set concaveCells
Face interpolation weight : minimum: 0.1792 average: 0.478164
Face interpolation weight check OK.
Face volume ratio : minimum: 0.0522973 average: 0.895213
Face volume ratio check OK.

Failed 1 mesh checks.
".

Should I go on with work on the mesh or should I look somewhere else?

PS: I am using snappyHexMesh to get the mesh.

Thanks in advance!

[nikoscham]

Hi,

You should put a limit in the Courant number by adjusting the time step in cotrolDict:

maxCo    1.0;
 adjustTimeStep  yes;

I hope it helps!
Nikos