[Bartg]

Dear readers,


For my thesis I'm using a finite element flow solver to simulate the flow through a flume. The flow solver is capable of solving the flow in a 3D unstructured mesh constructed of tetrahedrons. However, the meshes I generate with Gmsh somehow seem to be too unstructured. Which leads too unsolvable and very slow runs.


At the moment I've tried to do simulations with both unstructured and structured meshes. Simulation with very coarse unstructured meshes go very well, however once I make the element size smaller, the flow solver only produces NaN values and doesn't run at all.


For the simulations with structured meshes I've used the transfinite technique to produce a very fine structured mesh. This mesh contains way more element than the unstructured one and the results are fine. However, in future runs I need to refine the mesh in certain areas which doesn't seem possible with the transfinite volume technique in 3D.



Does anyone have any what could possibly go wrong in this case? And is there a way to improve the quality of a 3D gmsh mesh? Can the structure of the mesh be improved somehow?


Thanks in advance!
Bart