restraining normal velocity vector in a curved surface

Hi all,

I'm trying to emulate a two phase flow with the laminar single phase module, but I could not find a way to restrict the normal velocity from flowing through a curved surface.

It's like a slip wall boundary condition (U dot n) in the module, but instead I wan't to introduce a realistic shear stress.

I tried making 3 pointwise constraints where I used realdot(abs(spf.U),nx), realdot(abs(spf.U,ny), realdot(abs(spf.U,nz) at the interface, but I'm still having flow through the surface.

Is there any suggestions to prevent the flow from flowing through a curved surface, but still retains the tangential velocity?

Thank you!

TJ