[1995robert]

Hi,

For an assignment I am trying to model slip for the extrusion of a polymer (so a viscous fluid). I see a lot of models that use the full slip option in ansys (a zero-shear wall), but I think my solution is somewhere in between full stick and a full slip boundary.

Consider the case of a simple tube with a pressure inlet and a pressure outlet. For this case I want to create a certain wall boundary condition that calculates, based on the pressure, if the material will stick or if it will slip at the wall. So that I get a similar result as I have sketched in the attachment. The velocities are small so it can be considered as a laminar flow.

So first the pressure is high and the material sticks to the wall, but further to the outlet the pressure decreases up to a point where the material starts to slip. The velocity of the material will then increase until a full slip situation is reached. Here the velocity of the material at the wall is equal to the average velocity.

Does anyone know if such simulation has been performed before? Or does anyone know how I could model it?

Kind regards,

Robert