Hello,

I am modelling natural ventilation of an office with star-ccm. I want to get the the age of air in the office so I defined a new region at the window to release the scalar.In this region I have the scalar source set to 1/density. In the air properties I have set the Schmidt number to a high value to reduce molecular diffusivity.

This should be correct, shouldn't it? I am asking this because I seem to be getting extremely small values, e.g circa 0.01-0.1 s, for 60 m^3 room with 20m^3/s ventilation rate. I assume values should be circa 3 s? Am I doing something wrong?

Fixed it; I just hadn't the source term included in all other regions

Dude, why have you increased the schmidt number to high value, what is the reasoning behind this? what is the rationale?