Onset of turbulence induced by a Kelvin‐Helmholtz vortex

A two‐dimensional MHD simulation of the Kelvin‐Helmholtz (K‐H) instability in a non‐uniform density medium shows a strong development of turbulence through non‐linear instabilities. The difference in density between the two media plays a crucial role on the fast turbulent mixing and transport. The onset of the turbulence is triggered not only by secondary K‐H instability but also by Rayleigh‐Taylor (R‐T) instability at the density interface inside the normal K‐H vortex, whose onset mechanisms are attributed to the centrifugal force of the rotating motion. The secondary R‐T instability alters the macroscopic structure by transporting dense fluids to tenuous region, while the secondary K‐H instability is just a seed for the turbulence. The onset mechanism and the formation of the broad mixing layer give a new understanding of the mixing process in a variety of geo‐ and astrophysical phenomena.