How to simulate very slow flow?
 

Hello FLUENT users, my problem is how to simulate a very slow outflow rate, about 1-2 drop per minute, estimated flowrate is 5.3e-05~3e-05kg/s.

At moment, I got a simulation result on 3D model that velocity fluctuates quickly and vortical flow appear in some areas. Residuals curves seem ok. The model is that fluid in a container flow through a very thin oriface and then reach a short pipe. I defined steady, laminar, onephase, no energy conditions, almost all default settings.

Anybody know what kind of settings can solve out the flow fluctuation for this kind of small size gap and slow fow rate scenario? I am using FLUENT 5.5. Thank you in advance.