As an ejecta curtain advances through an atmosphere, it creates a vortex ring. By analogy with smoke rings, the curtain-driven vortex ring develops instabilities that result in waves. The number of these waves depends upon the aspect ratio of the vortex ring (i.e., the ratio of the core vortex radius to the vortex radius) and the Reynolds number (or strength) of the flow in the vortex ring. In ...

When a stably stratified density interface is embedded in a region of strong velocity shear, hydrodynamic instabilities result. Here we generalize the stratified shear layer to allow an offset between the centre of the shear layer and the density interface. By including this asymmetry, and keeping the density interface thin with respect to the shear layer, the asymmetric Holmboe (AH) instabilit...

Flow-induced instabilities that lead to non-uniform stationary flow profiles have been observed in many different soft-matter systems. Two types of instabilities that lead to banded stationary states have been identified, which are commonly referred to as gradient- and vorticity-banding. The molecular origin of these instabilities is reasonably well understood. A third type of instability that ...

Abstract Free-stream turbulence (FST) alters the boundary layer of wind turbine blades, changing hydrodynamic stability and near wake. Large-eddy simulations (LES) a blade section with laminar separation bubble for several intensities ( TI ) Reynolds number 10 5 are performed. The effects boundary-layer streaks generated by FST on Tollmien-Schlichting (TS) Kelvin-Helmholtz (KH) instabilities an...