Hello Eric and DrAmine.

In fact, it’s like the bottom plate has some holes where the fluid enters and leaves with a certain velocity defined by a boundary condition: (du/dy = alpha/ sqrt(k)) * (ui – um). That is, I need to set this condition exactly on the bottom wall.

Note that if this problem were to be solved analytically, I would have two boundary conditions.

(1) When y = 0 ==> du/dy = alpha/ sqrt(k)) * (ui – um)

(2) When y = h ==> u = 0

For the top plate the boundary condition it’s just a no-slip condition that can be set easily by fluent. But on the bottom plate I would need to put the equation: du/dy = alpha/ sqrt(k)) * (ui – um).

In short, what I really need to know how I can put an equation as a boundary condition on the bottom plate.

!Note that the plates are fixed.