[syoon]

Hello.

I'm doing a calculation which simulates a steam turbine diffuser.
I generally use a local time step which I gradually increase from 1 to 50.
This is generally okay for most of my cases.

However, for some outlet boundary conditions, the calculation does not converge and the flow separates significantly.
When I have these cases, I can often (not always!) make the solution converged by increasing the local time step to a very large number (say 200)

I wonder what this means.
Does it mean that my actual time step (delta t) is increased significantly and misses small time scale fluctuations?

Kind Regards,