Direct numerical simulations of incompressible Rayleigh–Taylor instabilities at low and medium Atwood numbers

Direct numerical simulations of two-dimensional (2D) and three-dimensional (3D), single-mode multi-mode, incompressible immiscible Rayleigh–Taylor (RT) instabilities are performed using a phase-field approach high-order finite-difference schemes. Various combinations Atwood number, Reynolds surface tension, initial perturbation amplitude investigated. It is found that at high numbers, the if significant, could prevent formation Kelvin–Helmholtz type within bubble region. A relationship proposed for vertical distance spike vs number. The reaccelerate after reaching temporary plateau due to reduction friction drag as result vortices also momentum jet traveling upward interface 3D instability grows exponentially; however, higher number and/or lower in noticeably larger area growth. shown multi-mode RT initially displays an exponential growth rate similar instabilities. Due collapse merging individual instabilities, strongly dependent mesh resolution rate. However, ratio kinetic energy over released potential exhibits almost steady state growth, with values around 0.4, independently resolution.