[acakaacaka]

Hi I want to kind of damp my solver when the flow field become unstable. My idea is to calculate the max mach number inside my air domain and multiply the time step a factor of 1/100 if Ma > 3 and do nothing if Ma < 3.

However I get this Error Message
Bad expression value 'TSF' detected in parameter 'Physical Timescale' in object '/FLOW:Flow Analysis 1/SOLVER CONTROL/CONVERGENCE CONTROL'.
CEL error:
A cyclic dependency between expressions has been detected while processing the expression assigned to 'Physical Timescale'.
The cycle detected is as follows (there may be others):
MaxMachNumber -> MaxMachNumber.

So is this method not possible?

[ghorrocks]

I have never had success in doing automated convergence functions like what you propose. You could look at it this way - if things like that did work it would already be in the solver.

In my experience, if a simulation has already gone out of control enough that the flow field is giving Ma=3 it is not recoverable. You have to start the run from the beginning again with a smaller physical time scale from the beginning (or at least a time where everything is converging well).

So I would start a simulation like this with a small time scale, and after it has run for a while and is converging nicely I would use the "Edit run in progress" option to manually increase the time scale. Observe the resulting convergence, and if the convergence starts zig-zagging then quickly reduce it down again.