[xkang]

Hi guys,
i am doing a 3d supersonic nozzle simulation using fluent. i use a quarter symmetric geometry for simulation and give a big space outside of nozzle exit. the geometry is showed below.Paint.jpg
currently my problem is the mass flow rate of simulation is much less than the result i get from experiment.

if the mass flow rate of simulation result is 1/4 of experiment result, it is reasonable for me because the simulation is only for a quarter of nozzle. but the simulation result is even much lower than that.

So does anyone have a idea why this happen?? thank in advance!!!!!!