Hydrodynamic Stability of Two-dimensional Jet near the Nozzle Exit

Abstract

The linear stability of two-dimensional jet issuing from a nozzle is considered from the view point of local similarity that is found while obtaining the basic flow by means of finite difference method. The results show that the local similarity can be used in the linear stability analysis when the Reynolds number is moderately large (Re_L>100). In the case of low Reynolds numbers, since the nonparallel effects become apparent it is needed to carry out the stability analysis by using the basic flow's local similarity which can reproduce the velocity distribution at certain Reynolds number from a known one. And the neutral stability curves which are not coincide before reaching the similarity region with that of Bickley jet are presented by considering the local similarity variable ξ(=x/Re_L) as a parameter. However there is a limitation in usage of this local similarity, which is also discussed.