Terminal velocities and vortex dynamics of weakly compressible Rayleigh-Taylor Instability

The evolution of Rayleigh-Taylor instability (RTI) for weakly compressible fluids was numerically simulated using the smooth particle hydrodynamics method. It was found that the speed of spikes and bubbles in most cases will reach a stable value, which is called terminal speed. The calculated terminal speed of the bubble was found to be systematically higher than the theoretical model based on the potential flow hypothesis. This deviation could be modified by including the vortex effect on the terminal speed of the bubble. A significant correlation between the bubble speed and the vorticity in the bubble head was found during the whole evolution of RTI. The analysis of the vortex dynamics in the bubble head region during the terminal speed stage shows that there is a balance between the baroclinic production, viscous dissipation, and convective transport of the vorticity. (c) 2022 Author(s).