LARGE-EDDY SIMULATION OF LONGITUDINAL STATIONARY VORTICES

The response of longitudinal stationary vortices when subjected to ran dom perturbations is investigated using temporal large-eddy simulation . Simulations are obtained for high Reynolds numbers and at a low subs onic Mach number. The subgrid-scale stress tensor is modeled using the dynamic eddy-viscosity model. The generation of large-scale structure s due to centrifugal instability and their subsequent breakdown to tur bulence is studied. The following events are observed. Initially, ring -shaped structures appear around the vortex core. These structures are counter-rotating vortices similar to the donut-shaped structures obse rved in a Taylor-Couette flow between rotating cylinders. These struct ures subsequently interact with the vortex core resulting in a rapid d ecay of the vortex. The turbulent kinetic energy increases rapidly unt il saturation, and then a period of slow decay prevails. During the pe riod of maximum turbulent kinetic energy, the normalized mean circulat ion profile exhibits a logarithmic region, in agreement with the unive rsal inner profile of Hoffman and Joubert [J. Fluid Mech. 16, 395 (196 3)].