Late-Time Vortex Dynamics of Rayleigh-Taylor Instability

We investigate late-time dynamics of the Rayleigh-Taylor instability, from long-time computations using an adaptive vortex method. The vortex method successfully simulates the complex disordered interfaces of the Rayleigh-Taylor instability with fine resolutions. The numerical results show that at a late time, the tails of the bubble and spike are elongated, the interface has a secondary instability, and the inner roll-up is highly distorted. In a weak density stratification, both the bubble and spike exhibit late-time reaccelerations, after converging to constant velocities. It is found that strong vorticities are evolved at the tails of the bubble and spike, and drive the acceleration of the bubble and spike.