The Instability Of Dual Cylinder Vortex Layer

The non-uniformity of the basic flow interaction with the ambient air,viscosity and non-linearity are main elements,which affect the stability of the vortex layer. Cylinder vortex layer is unstable at Reynolds numbers above certain critical values,and under these conditions the steady laminar flow is replaced by a turbulent flow. Rayleigh shown that there is always a fastest growing mode in the vortex layer. The fastest growing mode would become dominant one and would be the mode observed in practice.This paper obtained the necessary condition for the vortex layer, the wave-number of the fastest growing mode and the maximum value of increasing rate of the disturbance by the theory of linear stability,the method of normal-mode analysis and the fact that the disturbed flow is irrotational on each side of the cylinder vortex layer,on the condition that the basic flow is uniform, incompressible,inviscid and irrotational.