Confusion about the wall oundary conditions.
 

I want to define a wall with some flux inside the flow domain, where I know the flux velocity. I try to set the wall boundary condition in two methods.
1, With a no slip boundary condition, but set the wall velocity to the flux velocity.
2, set the no slip boundary condition without wall velocity, but with source term, where I define the continuity source and velocity source.


I'm wondering about which one is he correct one, and what make the difference? If we look back to the equations, the condition that wall is defined with velocity has nothing to do with the equation itslef. But the method with source will add the additional term to the original equitions. Please explain it a little bit, thanks you all in advance.