[Ollie West]

I am conducting a transient simulation of incompressible flow past a cylinder and I'm trying to model the cylinders oscillations induced by the flow (using the DFBI tool).

I'm having problems with convergence, but I think I have the correct numerical settings now however.

My questions is, how does Star-CCM+ use the specified CFL number? As I specify a time step, the mesh I created in ICEM has a given spacing and I specify the inlet velocity. All of these terms can be used to calculate the free stream CFL number, so why do I need to specify one to Star-CCM+? Does it somehow modify the time step if the CFL number is going to go above my specified value?

My simulation is using an Implicit time method.

I tried reading documentation on this but it wasn't very clear to me.

Thanks in advance.

Ollie.