Slip vs noSlip BC
- The noSlip boundary condition is an alternative to the zero fixedValue boundary condition for velocity. There is no difference between them.
- The slip boundary condition erases the normal component of the variable at the patch and keeps the tangential components untouched. It is very similar to the symmetry. Keep in mind that the symmetry is a boundary type, whereas the slip is a boundary condition which can be applied on boundary patches of type wall and patch respectively.
Figure: Sketch of velocity profiles for noSlip and slip boundary condition.