Oscillatory Flow in FLUENT

phy

hi

I am trying to simulate a periodic oscillatory flow. there is a temperature gradient two different wall, fluid is inside between these walls.

flow is steady, if temperature gradient has lower values. if temperature gradient is high enough, steady flow transition into Periodic oscillatory flow.

How can I simulate in FLUENT and which model is suitable for this problem.

in steady flow, I have to use Bossinesq approximation and I set Marangoni stress for free surfaces.

Thanks