Buoyancy time?
 

In the CFX output of a thermal calculation, there is a line towards the top of the .out file giving the "Buoyancy time". It is not referenced anywhere in the documentation as far as I can tell. Anyone know what it is?

I am not sure, but CFX does give a number of reference values of things like global Re number, Mach number and things like that. These are simply estimates so the user can make sure the overall simulation is approximately correct. For instance if you were modelling flow over a 747 and it said the global average Re was 10 then you would suspect something was wrong.