can you give some additional info?
What hardware do you use for cfd? (processor, number of cpus, RAM)
In you "ParaviewCut" pic from above I can see that your mesh (the meshed sub-body, right?)
contains more than 1,2 Mio FEM-cells. When I extrapolate this mesh refinement to the complete flow
domain, you will get approx 10 Mio cells
What calculation you will run? I mean, is the sub submerged or do you want to simulate a
free surface (sub not submerged).
Is the sub your "original" hobby-model or is it scaled up to the real world?
I am wondering why you do not use the FreeCAD cfd-workbench.
You have 3 different meshers (gmsh, snappyhexmesh+blockmesh, cfmesh)
with the options of mesh-refinement and turbulence (boundary-layers).
again: stunning project!