Phase of particle-level velocity perturbations determines the fate of Rayleigh–Bénard convection cells in 2D Yukawa liquids

Abstract

Using “first principles” molecular dynamics (MD) simulations, the sensitivity of two-dimensional Rayleigh–Bénard convection cells (RBCCs) to the phase and amplitude of particle-level velocity perturbations is demonstrated in strongly coupled Yukawa liquids. We find that RBCCs are retained only for “odd” phase values of particle-level velocity perturbations, whereas, for “even” phase values, RBCCs undergo transition to a horizontal shear flow, which eventually evolves to a horizontal shearless parallel flow. The parallel macroscale flow grows algebraically before saturation, and the growth rate itself is found to increase with the amplitude of the perturbation. The fluid enstrophy as a function of time constructed from MD data shows the existence of a credible minimization mechanism under play, for such transitions.