[fchan]

Hi everyone,

I’m currently trying to simulate a pitching airfoil attached to a fixed body. As SU2 does not support non-conformal interfaces, the only option available within the existing SU2 code is to use the external kind of grid movement (can't use rigid motion, rotating frames or moving walls).

Unfortunately, I’m having trouble with the external mesh motion type, especially in 3D: the mesh smoother keeps diverging (?), even with very small changes in the pitch angle (0.05 degrees crashes the solver). I actually get negative volume cells even if my original grid does not contain any. The grid currently used is viscous and is built to have a y+ value of 1. Wall cell height is therefore small (2.5e-6 m).

Prior to running these 3D cases, I tested SU2 features in 2D. While testing, I have found weird grid solver behavior when running parallel 2D test cases. In fact, the volume grid solver requires more linear iterations as the number of partitions is increased, as seen in the table below. The number of cells for the 2D case is 47600.

np	avg niter
1	326
4	360
32	381
84	389
252	409

Following the idea that more partitions seems to destabilize the volume grid solver, I tried to reduce the number of partitions I used for another 3D test case (257 400 cells) and it actually stopped crashing when I used 4 partitions or less. This is good news, however impractical as running 3D cases on 4 partitions requires quite a bit of time.

I had a look in the code, but couldn’t find anything.

Does anyone have any idea of what’s happening? Has anyone else encountered such problem?

I'll check if I can reproduce the problem with a grid in the TestCases folder with a new configuration file and update accordingly.

Regards,
Frederik