Discussion of "An Experimental Study on Turbulent Circular Wall Jets" by Adrian Wing-Keung Law and Herlina

Studies on turbulent circular wall jets mostly deal with the kinematic behavior of the jet. Hence, the experimental results reported by the authors will be of specific interest in the case of effluent disposal near the bottom of an aquatic body. Application of a nonintrusive technique for measurements of the velocity field and the concentration distribution in the jet has helped to give credence to the existing data, some acquired by less sophisticated intrusive techniques. The three Reynolds numbers adopted in the experiments have resulted in turbulent flows devoid of viscous effects in the free shear layer. Consequently, the typical wall jet profile on the central plane of symmetry is independent of the Reynolds number and exhibits similarity. Velocity distribution covering a larger range of z/zm/2 values have been worked out in their experiments which shows that the principle of similarity is valid even near the edge of the shear flow. Further, the distribution follows Verhoff's empirical curve. Though such a feature was assumed in the past (Pani and Dash 1983) for computing the forward momentum flux of three-dimensional wall jets, it lacked experimental support.