Direct numerical simulation of a differentially heated cavity of aspect ratio 4 with Rayleigh numbers up to 1011 - Part II: Heat transfer and flow dynamics

This is the second of a two-part paper on five direct numerical simulations of a differentially heated cavity of aspect ratio 4 with adiabatic horizontal walls (Rayleigh numbers based on the cavity height Ra=6.4×108,2×109,1010,3×1010 and 1011,Pr=0.71). The numerical methods and the time-averaged flow results were presented in the Part I. The heat transfer and the flow dynamics, including the turbulent statistics, the global kinetic energy balances and the internal waves motion phenomenon, are herewith described and discussed. The power-law scalings of the total kinetic dissipation rate and the Nusselt number suggest that a state of transition to a new scaling regime has been reached for the highest Ra.