reverse flow at pressure inlet affecting solution
 

hi friends,
i am modelling a standard pump sump problem using fluent. i am using VOF model for multiphase and ke-relizable for viscous formulation. gravity and buoyant formulation is enabled. plz see the pic attached for problem description. the top surface of air domain is defined as pressure inlet..i am running a transient simulation and keep getting reverse flow error at the pressure inlet...this is affecting my solution in a way that the streamlines on the interface of air and water enter the air domain...as far as know this should not happen!.....please give me some suggestions...
thanks in advance. have a good day :)