We establish the existence and regularity of a unique weak solution to turbulent flows in a bounded domain Omega subset of R-3 governed by the Leray-alpha model with Navier slip boundary condition for the velocity. Furthermore, we show that when the filter coefficient alpha tends to zero, these weak solutions converge to a suitable weak solution to the incompressible Navier Stokes equations subject to the Navier boundary conditions.
Finally, we discuss the relation between the Leray-alpha model and the Navier-Stokes equations with homogeneous Dirichlet boundary condition.