Dear sirs
I think I found a DISAGREEMENT in the computing of Mean age of fluid in the exhaust (Theoretical value V/Q) written in Solver log file.
The value to compare is theoretical value simple computed as (V/Q) where V is the volume of the test environment and Q is the volumetric flow rate at the inlet.
The DISAGREEMENT is found in SimScale Advanced Tutorial: Thermal Comfort in a Theater Room.
The values read from Solver log file are 3277 (see figure) and 3283 seconds for Design 1 and 2 respectively.
The other values are 3141 and 3156 computed using Volumes 691.1 and 694.4 m3 respectively and 0.22 m3/s flow rate prescribed in boundary conditions.
The DISAGREEMENT is approximately 4 % for both designs.
To the contrast in the
Validation Case: Mean Age of Air in a Room
this DISAGREEMENT is less than 0.6 % for all validated mesh densities and does not change during time iterations.
Conclusion: The DISAGREEMENT in question is not a consequence of (a) mesh density and (b) non converged solution.
And »must« be an »bug«. It could be also mistake in my simple analyse (after a few days and nights 
of nonstop thinking).
By the way. Small inconsistence is also found in Tutorial Thermal Comfort in a Theater Room. The prescribed volumetric flow rate in tutorial text is 0.3 while actual value in the project is 0.22 m3/s for both inlets together.
In my opinion the tutorial Thermal Comfort in a Theater Room is an excellent case research demonstrating capabilities of CFD in HVAC and the numbers should match.
Dr. Matjaz Ramsak
University of Maribor
