residence time
 

This is probably CFD related since tracer tetsing commonly used for validation purposes.

I have conducted a tracer test on a vessel. The data produced a mean average residence time of 44 minutes. The space time (volume/volumetric flowrate) was calculated as 33 minutes. There was a bit of dynamic flow condition so I used averaged flow to calculate space time. Is it possible to get an average residence time less than the space time ? If so under what conditions of flow ? (eg. recirculation) CFD did predict a large re-circulation region and a fast plume. I'm interested in any comments .