Transient Solution looks like Steady State
 

Dear Experts,

I am running into a very weird problem. I am simulating a whistle, a real pea-less whistle which you use in sports. It is a 2-D model. I have run the simulation with velocity inlet + Pressure outlet. In the first 3000 time steps, I could see the vortex forming then disappearing periodically. However, after some more steps, the solution would converge quicker (2 iterations or 1 interation) and the result looks like steady state. The vortex is no longer forming and disappearing.

Please let me know, if you have experienced any similar situation and also if you have any solution or suggestion.

Thank you very much.

Derek