Average velocity profile

Hello everyone,

I simulated fluid flow in a medium composed of porous matrix overlaid by a channel (attached figure). I am going to plot the average velocity profile along the length to examine the continuity of the velocity profile at the interface of the free/porous regions. The only thing I could do was to get velocity profile for outlet boundary only(attached graph). Do you know how could I get average velocity profile? I tried line integration and so on but they give me only one value. Instead of local velocity value at the outlet I am interested in averaged velocity values along the length.

Any input is highly appreciated.

Regards,
saeid