2D vs 3D in relation to pressure gradient
 

Hello everybody,

I would like to know, more or less, an explanation of the way a simulation of a 3D rectangular channel affects the pressure gradient (a bigger one or a smaller one) in relation to a simulation of a 2D rectangular channel. Because I know that when I simulate 3D channel I take into consideration 2 walls more that restrain the velocity, but what is the effect on the variation (roughly) of pressure's gradient.

Thanks for any advice and best regards

Isa