Convection in Fluids 352.3 NS???F System for a Thermally Perfect GasFirst of all we observe that, from the thermodynamic relation (2.6), we canwriteT???S????? T=???e????? T???p??2,and the Maxwell relation (2.10b) allows this to be written asT???p???T p= p ??? ??2 ???e????? T.Now, we have the de???nition:A perfect gas is a material for which the internal energy is the sum of theseparate energies of