Hi all,

let us assume a flow in simple pipe (air).

Step 1: I used mass flow rate boundary condition at inlet and outflow boundary condition at outlet. I calculated pressure values at inlet and outlet in post processing step from pressure contours.

In step 2 , I used the above obtained pressure values (Total pressure values at inlet and Static Pressure value at outlet)as my pressure inlet and outlet boundary conditions respectively for the same model.

Now question is I am not getting the same mass flow rate at inlet as in step no. 1

How do you obtain your in- and outlet pressure values? Mass weighted or area weighted average from surface integrals or what? I guess only if you write profiles of total pressure at your mass flow inlet and static pressure at your outflow the same massflow can be reproduced.

cheers Max

I gave total pressure at my mass flow inlet and static pressure at my outflow. I am not getting back the original mass flow rate.

If you have time try for a simple problem.

thanks for your reply

vijay