Tets vs Hexs
 

Hi, I'd like to ask two things about tetrahedral meshes:
1- People recommend not using them for transient flow. Why?
2- Do I need to make my courant number smaller if I use them?. I mean, the distance between cell center and face decreases if I use a triangle.


Edit, what I have found so far: according to a mesh quality tutorial by Joel Guerrero, triangular meshes are easier to adapt to geometry, but squares can be aligned with the flow, and to do so reduces face interpolation error.