example of pressure-outlet boundary condition
 

hi all,

I have uploaded some screenshots.

First one is total model and it has a lots of holes on it.

Second one cylindrical is fluid cell zone.

Fluid domain creating in each holes are to extended some more

Last one is pressure outlet bc. As you can see it is not hole diameter due to model shape. That is why pressure outlet volume flow rate in surface monitor always is fluctuating.

Any thoughts?

Maybe face applied in pressure outlet should be changed? or something like that ?

example of pressure outlet bc
 

Screenshots are attached.

Residuals and volumetric flow rate in pressure outlet bc are attached.

problem solved!