Using 3D model data as input for 2D model

Hi Everyone!

I have a 3D model with coupled flow and electro-chemistry equations. The equations are weakly coupled, so I know from previous experience that I can run the flow and electro-chemistry separately. I usually run the flow model and the I directly use the velocity field as an input for my electro-chemistry equation. This gives me satisfactory results.

From my experiments I know that although, the flow is 3D, the results from electro-chemistry are mostly the same over 90% of my domain. So, I was wondering, if I can run the 3D flow model and use a slice of that model as my flow input for my electro-chemistry equation? How would I mesh the 2D and 3D domains so that I don't lose any relevant information?

Thanks!
Sri.