Steady flows of incompressible Newtonian fluids with threshold slip boundary conditions

We give some wellposedness results for the time-independent Navier-Stokes equations with threshold slip boundary conditions in bounded domains. The boundary condition is a generalization of Navier’s slip condition and a friction-like condition: for wall slip to occur the magnitude of the tangential traction must exceed a prescribed threshold, independent of the normal stress, and where slip occurs the tangential traction is equal to a prescribed, possibly nonlinear, function of the slip velocity. In addition, a Dirichlet condition is imposed on a component of the boundary if the domain is rotationally symmetric