Meshing suggestion

Hello everybody. I request, if it’s possible, some little suggestion reguarding the mesh settings in a 2d case. I understand this part is more related to openFoam, but i found myself not so able to transport OF scripts inside butterfly.

Anyway the case i set up works fine in the Y and X direction, but diverge in the -X (f course i change the inlet and outlet boundaries in every cases). Moreover, increasing the velocities to 15 m/s makes every direction cases to diverge.

I understand this is caused by a poor meshing, but i’m not able to understand how to fix the problem. What i tried until now is to increase the level of the refinement region to 3 and decrease the cell size to {1;1;1}, but the series still diverge.

I upload the GH file (i ask sorry for the mess inside). (471.5 KB)

EDIT: i just found one of the problem was the snap function of snappyhexmesh off. Now it supports high velocities. Anyway suggestions are still very welcomed

This might also be part of the problem: