2 material Couette flow
 

Hello.
I'm beginner of fluent.
these days, I have been making 2 material Couette flow.

Upper wall moving velocity : 0.01 m/s
Bottom wall fixed
above the bottom wall, there is water layer(1mm)
above the water layer, there is oil layer(1mm)

Upper moving wall draw the oil.

In this situation, I don't know how to set-up the middle point(between water and oil) on the Gambit or fluent.
it's not wall then what?
I try it by wall, interior, interface. but I fail to make flow.

please help me.

the middle is a free surface, you should not set any boundary condition at that plane. it is a multiphase flow problem with free surface. tried to use VOF method to identify the free surface betweet two fluids