Meshing error for CFD simulation

eliot_drou · February 8, 2024, 3:27pm

I’m trying to analyse winds on a site in order to determine the way we could create passive cooling in our building. But i get a meshing error telling me “an error occured” without any more information. My geometry doesn’t seem to have any problem but i might be missing something as i’m new to Simscale, I also tried modifying some of the meshing setting but it still doesn’t work out. Can somebody help me find a solution ?

Thanks in advance !

The project, simulation and geometry can be found here: CHU Poitiers | SimScale Workbench

here’s the meshing log, it doesn’t seem to shows any mistakes:

Model import took 1.088386847s.
Maximum precision of model and its entities: 0.0004881006724017567 m.
Absolute small feature tolerance: 0.3 m.
Gap refinement size is reaching lower cell size cap for 1 regions. Consider lowering model tolerance if resulting mesh fineness is too coarse.
Determined sizing is reaching lower cell size cap for 53 faces. Consider lowering model tolerance if resulting mesh fineness is too coarse.
Number of faces after 5m0.000253028s: 5166
Surface meshing took 8m41.032500977s.
Number of cells after 13m1.591364606s: 1238895
Number of cells after 17m22.120758124s: 12511336
The mesh may be finer than desired. Please check the model and the mesh settings
Number of cells after 21m42.627273773s: 17051086
Number of cells after 26m3.175976579s: 16978087
Number of cells after 30m23.703508007s: 17019828
Number of cells after 34m44.135503362s: 17042824
Number of cells after 39m4.737003456s: 17049209
Number of cells after 43m25.25950568s: 17054792
Number of cells after 47m45.775502505s: 17057854
Number of cells after 52m6.270050902s: 17060377
Meshing took 54m12.237630703s. Starting mesh export.

goncalves · February 8, 2024, 4:16pm

Hi @eliot_drou,

Thanks for posting your question! The geometry seems to be a bit intricate to be solved by the standard algorithm. In this sense, it would be possible to generate this mesh changing it from Standard to Hx-dominant mesh. Please give it a go and let me know how it goes.

BTW, it seems you have about 500m of terrain, so be aware that for Large Scale simulations the correct approach would be using LBMM analysis type.

best,

eliot_drou · February 9, 2024, 10:29pm

Thanks for this advice, I tried the Hx-dominant mesh, it gives me more information about the error but still doesn’t complete the meshing.

Here’s what the error text tells me :
The tesselated surface is not closed. There could be a problem with the CAD geometry (such as self-intersections). Please inspect your geometry. Trying to proceed anyway.
Illegal triangles were found after surface tesselation. There could be a problem with the CAD geometry. Trying to proceed anyway.
Gap and region refinements couldn’t be applied for all bodies as there are non-solid bodies present.

Could you help me with this issue ?
During the creation of my geometry, I imported CAD from Revit and the topography volume seemed to have self-intersections. I decided to wrap it and then unite it with the buildings but it seems like it didn’t work out. This information might give you an idea of how I could proceed to get this simulation to work?

Thanks in advance,