Superimposed Wall Jet Velocity and Vorticity Fields

The velocity field is superimposed on the vorticity field as shown below.   It can be clearly seen that the fluid is entrained from the ambient into the vortices.  Also, as the upper vortices approach the surface, there is an upward ejection of the fluid from the wall.  The wall jet flow is highly unstable as compared to a typical boundary layer.  This strong flow-surface interaction is important in practical applications such as the film cooling consideration of flow over trubine blades of a jet engine.