[aa.g]

Dear all,

I am performing a static FSI calculation where I couple SU2 with an external structural solver using the CFluidDriver class through the python wrapper. Once the structural deformations are applied to the fluid surface mesh, the volume mesh is deformed using the StaticMeshUpdate method (I have found element stiffness based on inverse wall distance to be more robust for this).

My progress bottlenecks here, due to seemingly excessive memory requirements of the mesh deformation routine (beats my 32GB RAM for a relatively small 3M cell mesh ...). Having tried several workarounds, I have come to the following observations:

• Process crashes ("Killed" when running in serial, or a more informative "Exit status 9" when running in parallel) after calculation of the element volumes/wall distances: perhaps during the assembly of the stiffness matrix ? System Load Viewer spikes to >99.8% RAM Memory before crashing.
• For smaller deformations, it might happen that the deformation proceeds successfully.
• Increasing the number of deformation increments (DEFORM_NONLINEAR_ITER) seems to affect the issue as well. This is most likely related to the previous observation.

I hope this can give a reasonable overview of the context. The problem appears both with 5.0.0 and 6.0.0. Having struggled with this for a moment now, I would like to know the following :

• Are the reported memory requirements reasonable for the described case (over 32GB RAM for ~3M cell volume mesh deformation) ? If so, my machine is simply not sufficient ... although 32GB seems excessive for the calculation at hand.
• What settings in the Grid Deformation Parameters section of the .cfg could allow me to reduce these memory requirements ? Perhaps my setting of the solver (FGMRES), preconditioner (ILU) or the remaining parameters are not well-suited, although I suspect it is irrelevant if the problem is a large stiffness matrix.
• Bonus: Why does the amplitude of the deformation (seem to) affect the memory requirements of the volume mesh movement routine ? Is there perhaps some kind of "radius" outside of which elements are not included in the calculation, which depends on the boundary deformation ?

If anyone has experience with a similar process including the volume mesh deformation, any comment would be very welcome and helpful.