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MultiRegion heat transfer simulation with SnappyHexMesh and SplitMeshRegion |
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February 7, 2021, 10:24 |
MultiRegion heat transfer simulation with SnappyHexMesh and SplitMeshRegion
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#1 |
New Member
jackjiang
Join Date: Feb 2020
Posts: 10
Rep Power: 6 |
Hello Foamer!
I'm running a heat exhanger simulation acc. to attachment. (OpenFoam8 is used and please just focus on the geometry first) I got problem with splitMeshRegions after SnappyHexMesh, checkMesh showing I have 2 cell zones, (of course it should be, 1 for shell side and 1 for tube side) Code:
Create polyMesh for time = 0 Time = 0 Mesh stats points: 1798049 faces: 5023588 internal faces: 4998748 cells: 1612136 faces per cell: 6.21681 boundary patches: 6 point zones: 0 face zones: 2 cell zones: 2 Overall number of cells of each type: hexahedra: 1501608 prisms: 3104 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 107424 Breakdown of polyhedra by number of faces: faces number of cells 4 16 6 25944 9 48096 12 30664 15 2688 18 16 Checking topology... Boundary definition OK. Cell to face addressing 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 tube_inlet 3220 3961 ok (non-closed singly connected) tube_outlet 3220 3961 ok (non-closed singly connected) shell_wall 6960 7092 ok (non-closed singly connected) shell_outlet 4240 5098 ok (non-closed singly connected) shell_inlet 4241 5099 ok (non-closed singly connected) solid_external 2959 4975 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (-0.0349998 -0.0349998 -0.0500066) (0.0349998 0.0349998 0.0500127) Mesh has 3 geometric (non-empty/wedge) directions (1 1 1) Mesh has 3 solution (non-empty) directions (1 1 1) Boundary openness (-1.47295e-16 1.68262e-16 -7.27036e-17) OK. Max cell openness = 3.49386e-16 OK. Max aspect ratio = 3.64709 OK. Minimum face area = 2.9578e-09. Maximum face area = 1.16692e-05. Face area magnitudes OK. Min volume = 1.38181e-11. Max volume = 3.93085e-08. Total volume = 0.00038209. Cell volumes OK. Mesh non-orthogonality Max: 65.3388 average: 13.9728 Non-orthogonality check OK. Face pyramids OK. ***Max skewness = 4.25841, 16 highly skew faces detected which may impair the quality of the results <<Writing 16 skew faces to set skewFaces Coupled point location match (average 0) OK. Failed 1 mesh checks. End Code:
Using current cellZones to split mesh into regions. This requires all cells to be in one and only one cellZone. --> FOAM FATAL ERROR: For the cellZonesOnly option all cells have to be in a cellZone. Cell 39 at(-0.00979483 -0.0232375 -0.049804) is not in a cellZone. There might be more unzoned cells. From function int main(int, char**) in file splitMeshRegions.C at line 1629. FOAM exiting Code:
Number of regions:15 Writing region per cell file (for manual decomposition) to "constant/cellToRegion" Writing region per cell as volScalarField to "0/cellToRegion" Region Cells ------ ----- 0 703121 1 55375 2 55376 3 73376 4 73376 5 76176 6 55616 7 78576 8 53732 9 76176 10 73376 11 55376 12 73376 13 55377 14 53731 Region Zone Name ------ ---- ---- 0 1 shell 1 -1 region1 2 -1 region2 3 -1 region3 4 -1 region4 5 -1 region5 6 -1 region6 7 0 tube 8 -1 region7 9 -1 region8 10 -1 region9 11 -1 region10 12 -1 region11 13 -1 region12 14 -1 region13 a) live with it, just continue simulation with all these regions b) try to connect the tubes, for example make one inlet connect all of them? c) try to change code of splitMeshRegion to make it go trough a regions which are not connected (maybe my guess is not correct, so this idea may also lead to wrong direction) Please, any hints will be very appreciated! by the way, there seems a similar case been discussed, but I can't see a practical solution... multiple regions BR/Jack Last edited by jackjiang1989@gmail.com; February 9, 2021 at 21:29. Reason: add more information |
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February 9, 2021, 21:45 |
share one of the solutions
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#2 |
New Member
jackjiang
Join Date: Feb 2020
Posts: 10
Rep Power: 6 |
Hello,
Now I found the first solution. - to make tube side connection geometrically, I added a shared inlet. besides a "fully sealed" model, below 2 points are important, 1. in snappyHexMeshDict, point for locationInMesh should not be in either tube side or shell side, but in the solid wall side. Then you could got two nice meshed region for tube and shell. 2. Run splitMeshRegions -cellZones -defaultRegionName solid -overwrite, besides tube and shell, another region called solid will be generated. Just three of them totally. BR/Jack |
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heat transfer, multi region, snappyhesmesh, splitmeshregions |
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