The initial evolution of a turbulent axisymmetric wake at13; a macroscale Reynolds number of 1500 has been simulated by direct solution of the unsteady threedimensional Navier-Stokes equations using a (temporal) spectral scheme on the Flosolver Mk3 parallel computer at NAL A visualization of the flow is presented in terms of constant-vorticity surfaces. The simulation shows a complete sequence of events from formation of vortex rings through generation of azimuthal instability and appearance of streamwise structures to eventual breakdown into turbulent flow, and reveals explicitlycertain interesting features of the development of streamwise vorticity
