Vortex generation and deformation of the interface in three-dimensional Rayleigh-Taylor Instability

Abstract
We have performed 3-d hydrodynamic Rayeligh-Taylor simulations with initial perturbations with two modes to clarify nonlinear dynamics of the bubbles. By imposing two modes with different initial amplitudes, well defined bubbles with three different sizes, small, medium and large, can be formed. We pay attention to the generation of not only transverse vortex, perpendicular to the gravity, but also the longitudinal one, and relation between the bubble dynamics and the vortex. It is pointed that the longitudinal vortex is generated due to pressure gradient, parallel to the gravity, caused by fluid flow stagnated at the saddle and that three different bubble growth can be understood from the point of vortex dynamics view.