SUMMARYThis report presents an experimental investigation of the mean properties of turbulent, three-dimensional, incompressible air jets issuing into a quiescent air ambient from various rectangular orifices parallel to, and at the surface of, a flat plate. An analytical approach to estimate the shear stress distribution at the plate is also presented.The flow field of a three-dimensional wall jet is found to be characterized by three discinct regions in the axis velocity decay.From the results obtained it is concluded that for three-dimensional wall jets the maximum velocity in the flow in the near field exhibits a decay rate dependent on orifice geometry, while far downstream of the jet exit it decays at the same ra 4 .e as that in a radial wall jet flow field independent of orifice geometry.Furthermore, it is shown that the growth of the mixing layer normal to the plate is apparently independent oZ orifice shape while the near field spanwise growth is affected by initial geometry.