contour plot: mass flow difference
 

Pls ref attached pic.
simulation mode: transient, compressible.
I've specified mass flow rate in kg/sec in pre.
I've not get correct value in contour plot. why? my friend told that in compressible simulation you maynot get correct value, you will get only in incompressible mode only.
Is it true? pls explain

The contour plot is showing mass flow rate per element. You have to integrate that over the cross section to get the total mass flow rate. Your friend is correct, for transient compressible flow you will not get constant mass flow rate in general. It is due to the pressure waves, and how they take some time to travel up and down the domain.

ghrocks could you please tell me how cn i intergrate mass this in fluent

Try the fluent forum.