Slip
Use the Slip node to prescribe zero normal velocity, and therefor also zero tangential stress, condition on the boundary
This results in a so-called no-penetration condition where no viscous boundary layer is created. Use the condition in places where the viscous losses in the boundary layer are nonimportant. In this way it is not necessary to mesh the boundary layer resulting in fewer mesh elements.
Per default, the Slip condition uses a so-called discontinuous Galerkin or penalty formulation to prevent locking problems on curved surfaces.
Constraint Settings
To display this section, click the Show button () and select Advanced Physics Options.
Select Use weak constraints if you want to switch from the default discontinuous Galerkin (penalty like) formulation to a Lagrange multiplier formulation for the slip condition (this formulation is not suited for an iterative solver). The Lagrange multiplier formulation also prevents locking problems.