[FLASH-USERS] courant factor

[Riccardo Ciolfi]

 Dear all, 

I am trying to understand the definition of the variable cfl. Does it correspond to the courant factor Delta_t/Delta_x * v_max? 
Is this the same at all levels, so that Delta_t is reduced by a facotor of 2 together with Delta_x when moving to the next refinement level? Is there a simple way to enforce it?

I am using FLASH4.4 and for 1D hydro simulations I adopted the suggested clf=0.8 without any problem. When I move to 2D I cannot run unless I put cfl as low as 0.1. Is this expected? For coordinates with Delta_x=Delta_y, shouldn't be sufficient to reduce the courant factor by a factor of sqrt(2)?

Thank you very much for the attention!

 Best, 
 Riccardo Ciolfi