The influence of a spoiler on the development of a highly curved turbulent wall jet

A sharp edged spoiler increases the deflection angle of a curved turbulent wall jet significantly. The spoiler creates a large negative pressure gradient at the wall at the end of the channel which 'relaminarizes' the turbulent wall boundary layer in this region. This effect occurs only for spoiler heights above a certain value and Reynolds numbers below a certain critical value. A discussion of the streamwise component of the turbulent Navier-Stokes equation in orthogonal Cartesian coordinates for two-dimensional flow with wall boundary conditions shows that in the present case the 'ordinary' turbulent wall jet separates more easily than a wall jet with a 'laminar' wall region.