Reversals of large-scale circulation in turbulent convection in rectangular cavities

High Rayleigh number convection in a cubic cell with adiabatic sidewalls

“…Long term experiments revealed some specific features of the LSC, such as low-frequency oscillations with a dominating frequency, rare chaotic reorientations and/or reversals of LSC [19,21,31]. Rare and stochastic events with remarkable change of LSC structure is the intriguing problem itself.…”

“…These deviations are not caused by measurement errors but as we will show below in Section 3.3 are results of reorientations of the large-scale circulation. A particular feature of turbulent convection in cubic cavities concerns the low-frequency oscillations of LSC [31,32]. This very specific phenomenon was observed for a limited range of governing parameters and can be useful for CFD codes validation.…”

“…Complex spatial structure and temporal behavior of large-scale circulation in cubic cavities [31,32] raise important question about the sensitivity of LSC characteristics to specific experimental realization. Therefore we deliberately constructed two setups without coordinating their technical details.…”

“…Spontaneous inversions of large-scale circulation (LSC) for rectangular cavity with C ¼ 0:25 were found in [30]. Regimes of LSC in rectangular tanks of different aspect ratios were studied experimentally in [31], where it was shown that the LSC strongly depends on the small variation of the cavity thickness. Threedimensional convective flows in a cubical cavity at Ra ¼ 4:4 Á 10 9 were experimentally and numerically studied in [32], where the variety of dynamical regimes was observed.…”

Reversals of the large-scale circulation in quasi-2D Rayleigh–Bénard convection

“…the mean time between successive reversals has a strong Ra dependence in the former and is essentially Ra-independent in the latter (Brown & Ahlers 2006;Xi & Xia 2007). The importance of the corner rolls was also found later by a number of numerical and experimental studies in the 2D/quasi-2D system (Chandra & Verma 2011, 2013Vasilev & Frick 2011;Yanagisawa et al 2011;Wagner & Shishkina 2013). As the dynamics of flow reversals appears to have quite different dimensional dependence, the question then is whether flow reversals in the RB system in the 2D and 3D cases can be described by a unified framework.…”