Measured oscillations of the velocity and temperature fields in turbulent Rayleigh-B\'{e}nard convection in a rectangular cell

TL;DR

This study investigates temperature and velocity oscillations in turbulent Rayleigh-Bénard convection within a rectangular cell, revealing distinct oscillation behaviors and their dependence on Rayleigh number, with geometry influencing velocity oscillations.

Contribution

It provides detailed measurements of oscillation periods and their Ra dependence in a rectangular cell, highlighting the impact of system geometry on velocity oscillations.

Findings

Temperature oscillation period is approximately 74 seconds.

Velocity oscillation is observed near the sidewall with a period of about 65 seconds.

Velocity oscillation is affected by the system geometry, unlike in cylindrical cells.

Abstract

Temperature and velocity oscillations have been found in a rectangular Rayleigh-B\'{e}nard convection cell, in which one large scale convection roll exists. At $Ra=8.9 \times 10^{11}$ and $Pr=4$, temperature oscillation can be observed in most part of the system and the oscillation period remains almost constant, $t_T = 74 \pm 2$ seconds. Velocity oscillation can only be found in its horizontal component, $v_y$ (perpendicular to large scale circulation plane), near the cell sidewall, its oscillation period is also constant, $t_T = 65 \pm 2$ seconds, at these positions. Temperature and velocity oscillations have different Ra dependence, which are respectively indicated by Peclect number $Pe_T = 0.55Ra^{0.47}$ and $Pe_v = 0.28Ra^{0.50}$ . In comparison to the case of cylindrical cell, we find that the velocity oscillation is affected by the system geometry.