Centrifugal instability of turbulent wall jets along strongly concave surfaces

A theoretical consideration of Taylor-Goertler centrifugal instability of turbulent wall jets along strongly concave surfaces, as a result of which longitudinal vortices are expected to occur as secondary flow in the wall jets, is presented. The results show that the Goertler parameter G in the neutral state increases with increasing Reynolds number as a function of G-Re to the nth, with n = 1.00 to 1.05 in the Re range 30,000 to a million. It is concluded that the curvature b/B rather than G plays an important role in the present instability problem. The numerical results give the critical condition b/B sub cr = 0.08, which is in close agreement with the one obtained from stability theory when the effect of curvature on Reynolds stress is included.