Unsteady CFL number

[dylewiczk]

Hi,

I am running unsteady simulations within SU2 for compressible flow over a cone. I am not entirely sure I understand the unsteady CFL number within the code.

I want to maintain a certain maximum unsteady CFL number within the domain and based on that compute a global time-step. I want to keep the unsteady CFL number < 1 so I use an explicit scheme. When I specify unsteady CFL number to be 0.8 I get a ridiculously small time-step of 1e-13 order. At the same time, the solver runs just fine with unsteady CFL of 10 (mind I am using an explicit time marching scheme). My back of the envelope calculations indicate that the time-step size for my mesh/free-stream conditions at unsteady CFL 0.8 should be about of order 1e-9.

Has anyone experienced such problems with incredibly low time-steps computed for the unsteady CFL number in the past?