WaterGEMS Tank Mixing Model

Question

Hello,I 
 I have a few questions regarding tank mixing that aren't answered by the discussion page on this subject. 
 
 What type of tank mixing model is best suited for an elevated storage tank with a common inlet/outlet pipe? 
 What about for simulating tank stratification? 
 What about for separate inlet/outlet pipe? 
 
 Thanks! 
 Brett

Tom Walski · Answer

All tank mixing models are approximations. 
 
Most standard elevated tanks are close to completely mixed unless they are very large. 
 
Tall skinny metal standpipes are the tanks most likely to stratify. In that case the LIFO (Last in first out) or 2 compartment models are best. 
 
Tanks with separate inlet/outlet pipe depend on the configuration of the tank. If there are internal baffles to maximize detention time such as chorine contact tanks, you may approach the FIFO (First in First out) model. If there is plenty of inlet momentum and the tank is small, then the complete mix model may be best. If there are dead zones, you may need the 2 compartment model.

Tom Walski · Answer

That's getting into Computational Fluid Dynamics and we haven't seen much demand for it. It is still a bit of a niche art. Maybe one day.