A special phenomena in simulation rotor/stator int

Ji

Hello everyone,

When I use fluent simulate rotor/stator interaction in axial compressor(substract tip section and modelled as 2D problem), there is an interesting phenomena. That is, it will converge very slowly. it generally need over 10000~20000physical time steps(60 time steps for one period), not like that in turbine case in which only 1000 physical time steps(60 time steps per period) are enough. As I browse iterating history, it is found that there is always a long wave(5~6 times of final periodic wave) taking effect regardless of what back pressure is set.

What's wrong with my simulation?

Have you ever come across such a problem?

Regards

Ji