Prandtl number dependence of flow topology in quasi-two-dimensional turbulent Rayleigh–Bénard convection

• DOI: 10.1017/jfm.2024.550
• Publication Date: 2024-08-22T01:10:37Z
• Authors: Ze-Hao Wang; Xin Chen; Ao Xu; Heng-Dong Xi
• Keywords: Rayleigh–Bénard convection; Turbulent Prandtl number

To date, a comprehensive understanding of the influence Prandtl number ( $Pr$ ) on flow topology in turbulent Rayleigh–Bénard convection (RBC) remains elusive. In this study, we present an experimental investigation into evolution quasi-two-dimensional RBC with $7.0 \leq Pr 244.2$ and $2.03\times 10^{8} Ra 2.81\times 10^{9}$ . Particle image velocimetry (PIV) measurements reveal transitions from multiple-roll state to single-roll increasing $Ra$ , transition is hindered i.e. transitional Rayleigh $Ra_t$ increases We mapped out phase diagram change identified scaling : $Ra_t \sim Pr^{0.93}$ low range, Pr^{3.3}$ high range. The range consistent model balance energy dissipation time plume travel that proposed our previous while implies new governing mechanism. For first time, $Re$ acquired through full-field PIV velocity measurement, $Re Ra^{0.63}\,Pr^{-0.87}$ also propose horizontal promotes formation large-scale circulation (LSC), especially for case. Our proposal was verified by achieving LSC introducing driving force $Ra_H$ tilting cell small angle.