porous jump
 

In my problem, grain is stored in a cylindrical tank. The grain is modeled as porous zone (all props calculated as per 6.19.6 User Inputs for Porous Media in fluent manual. Now at the bottom of tank there is a perforated plate. There is significant leakage of gas from the tank thru this plate. How do I model it? Gravity in my model is off. The only force driving is diffusion force? How do I calculate parameters for porous jump? The velocity of flow is really really small thru this plate. Please advise as soon as possible.