Experimental and numerical study of turbulent penetrative Rayleigh-Bénard flow of water near 4 °C in a box-shaped container

Understanding the reversal process of the large-scale circulation will facilitate system recognition of turbulent penetrative Rayleigh-Bénard convection. The present work describes experimental and numerical investigations on the Rayleigh-Bénard flow of water near 4°C in a box-shaped container. The results indicate that the revised Nusselt number is slightly higher than average Nusselt number with adiabatic assumption. The Nusselt numbers from the simulations show good agreement with the experiment values. Large-scale circulation reversal becomes less likely with the increasing Rayleigh number and density inversion parameter. Reversal is not observed at large density inversion parameters and Rayleigh numbers. Large vertical velocity and temperature fluctuations at the center point are found during the reversal process. However, the Nusselt number is slightly affected by the occurrence of the reversal.