Suppression of Rayleigh-Taylor turbulence by time-periodic acceleration*

Turbulent convection, in the framework of Rayleigh-Taylor turbulence, is studied in the presence of an alternating, time periodic acceleration. By means of extensive direct numerical simulations of the Boussinesq equations, we discover a new mechanism of relaminarization of turbulence: The alternating acceleration, which initially produces a growing turbulent mixing layer, at longer times suppresses turbulent fluctuation and drives the system toward an asymptotic stationary configuration. Dimensional arguments and linear stability theory are used to predict the width of the mixing layer in the asymptotic state as a function of the period of the acceleration.