Calculating average velocity for planes - Confused!
 

Hi all,

I'm fairly new to CFD and have had to learn rather quickly.

I'm currently trying to compute the average velocity on a number of planes of differing heights in my model.

For each height in the model, I have created 4 planes - 2 small equally-sized strips running along the far edges and 2 larger equally-sized planed in the middle. Please see the screen shot below for clarification, each plane is a different colour.

I have entered the formulae for average velocity for each of these planes, but I'm getting identical numbers for the 2 small strips and equal numbers for the 2 middle planes, despite there being an uneven velocity distribution along the x-axis, see second screen shot.

The planes are slice planes, and have tried changing them to sample planes and varying the sample points, the numbers change but are still identical. I must admit however that I'm struggling on finding out precise definitions of these and the help literature is quite sparse.

QUESTION: What am I doing wrong to get identical values for these clearly different regions?

Apologies if this is a completely obvious question- I've not been given much time and support with this.

Thanks in advance!

Nick