I have a set-up where the two finite horizontal parallel plates have liquid between them. The bottom plate moves. I want the liquid to be fixed as originally patched at the top plate. Basically, i do not want water to move with the plate. Any ideas?

Hi, If I understand you right, you do not want the liquid that is adjacent to the top plate to move with the movement of the bottom plate? I guess as long as you have a no-slip condition at the top wall, it will not move with the bottom plate. You will however have a parabolic velocity profile between the plates. The liquid in between will move. Is this what you meant to ask? Phil

If on the other hand, you are looking at the liquid adjacent to the bottom plate and trying ensure it does not move with the plate, you might want to force a free slip condition (0% friction) at that plate boundary.

Phil

I have no-slip at the top & bottom walls. But, it still does move after a while at the top plate (though the boundary layer near the bottom moves faster). Thanks for the response. Any ideas?

I do not mind the liquid near the bottom moving. However, it should stop moving after a while (even though the bottom plate moves). But, I do not want the top layer of water to move at all. How do I impose free slip condition (0% friction)? Shall i do it on the top plate instead?

Thanks Again

On second thought

Shouldn't it be maximum friction (and not 0 friction) if i want the liquid to be fixed to the plate?

Well yeah, no slip corresponds to a friction coefficient of 1 And free slip a condition of 0 One suggestion could be to look more closely at your boundary layer meshing scheme. You might want to put in a few more grid points there. The only other way I can think of is to "artificially" make the water more viscous. You can change the viscosity, but be aware that this will also change the physics!

-Phil