Linear two-dimensional stability of a Burgers vortex layer

A linear stability analysis is presented for a stationary Burgers vortex layer in irrotational straining flow, to normal mode disturbances invariant in the direction of main flow vorticity. The whole neutral curve is calculated by combining numerical and asymptotic analysis. It is similar to that for free mixing layers which are always unstable, except that there is unconditional stability below a critical Reynolds number, in agreement with the long-wave asymptotic result by Neu [J. Fluid Mech. 143, 253 (1984)]. The Reynolds number compares shear flow vorticity versus stretching rate and diffusion, so both latter factors are stabilizing if strong enough. Neutral disturbances represent standing waves. (C) 1996 American Institute of Physics.