hi guys can any one tell me whats the difference between mass weighted and area weighted average. i want to calculate pressure drop bewteen inlet and outlet ant at few pre-defined interior surfaces. i am not sure what to use mass or area weighted average.

basically, mass-wg would be for "fluid" variables (density, velocity...) and area-wg for "surfacic" ones (to me).

so, for pressure drop between surfaces, it's more about pressure loads on plans. seems better area-wg

anyway, take a look at the equations in the UG to see which you like the most.