Similarity solution for flow over an unsteady nonlinearly stretching rotating disk

The unsteady laminar flow of an incompressible viscous fluid over a nonlinearly stretching rotating disk is investigated. The axisymmetric three-dimensional boundary layer equations are reduced into self-similar form with the help of new similarity transformation. The resulting coupled nonlinear equations are solved numerically using shooting method coupled with Range-Kutta 6 (RK-6). An exact analytical solution for the large stretching parameter is also presented. Some interesting observations are made while interpreting the results physically. Dual solutions are obtained due to the presence of unsteadiness parameter for the nonlinear stretching of the rotating disk. The analytical results reveal that for large stretching parameter the azimuthal velocity becomes negligible and the flow behaviors turn into steady state, which is the most surprising observation of the paper. These results are also verified numerically by solving original self similar equations using shooting method.