[astronome]

Hi Fluent users;
Actually, i have a problem while modeling a synthetic jet with cavity in Fluent. For those who don't know what does this mean: the configuration consists on a vibrating membrane at the buttom of a rectangular cavity, the upper edge of the rectagle contains a hole which represent the jet orifice..and of course the jet is injecting on a quiesent atmospheric air. To model the vibration of the membrane i've used the dynamic mesh feature with piston full udf/profile motion type. The membrane is modeled as a wall where the motion is imposed. The other boundaries are consideres as stationary walls exept the outlets where the condition is pressure outlet. I'm using a compressible ideal gas. A 2nd order upwind scheme is used with Simplec pressure-velocity coupling. Now the problem is i always have a "reversed flow" warning message at my outlet faces (3 faces)...i've tried to change a lot of parameters but nothing new..even after 20 cycles the reversed flow persists and the only the region near the orifice is solved..the entire domain remains unsolved.
So please, if anyone can help me out with this case cuz i need it very very soooon...
Thanks in advance.
P.S: Note that my configuration is symmetrical (only the half domain is modeled).