Greetings, 

I am working on the simulation of flow inside a centrifugal fan, the first stage of design validation was a steady-state simulation where everything ran smoothly.

For the next stage of my design, I must run a transient simulation (this is because I need to do acoustic analysis), however, despite a lot of attempts the solution diverges after a couple iterations, can't even complete one time-step. (I always get the floating point exception)

Has anyone faced a similar issue? Please find details below

Steady-state info

  1. Pressure Inlet
  2. Mass flow outlet
  3. k-w SST turbulence model
  4. rotational speed = 25,000 RPM
  5. Interface= Frozen rotor
  6. Monitor was placed to check the convergence of the pressure rise across the fan

As stated everything good with steady state.

For transient simulation I started with the same B.C's and a time step of 6.67e-6 (aware that I should do sensitivity analysis on this later on), I also started with the DES turbulence model and after failing with that, I tried some computationally simpler ones without success.

I think that summarizes everything, I appreciate any guidance or tip.

Regards