Behaviour of Mean Velocity in the Turbulent Axisymmetric Outer Near Wake


Department of Mathematics and Statistical Sciences, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana


An asymptotic study of the outer near wake of a long slender body of revolution is carried out. The long slender body is a cylinder which is kept parallel to the flow and takes the shape of a simplified geometry such as that of an underwater vehicle, a rocket or hull form of a ship model. The wake flow is axisymmetric and the analysis has been carried out without any assumption on the eddy viscosity but utilizing the general behaviour of turbulent shear stress in the near wake. The governing equations are solved with appropriate boundary conditions. Similarity analysis for the mean velocity characteristics is carried out which shows the existence of a logarithmic region in the normal direction in the overlap region between the outer near wake and the inner near wake. Also shown is the exponential decay of the mean velocity defect as freestream velocity is reached. Validation of the results of the analysis is done using available experimental data.