Centrifugal Convection

Centrifugal convection is a prosperous system that, in particular, allows the investigation of the high-Ra regime in thermal convection of Rayleigh–B´enard type, by increasing the rotation rate (i.e., by increasing the centrifugal acceleration). In addition, for any rotation rates, the system experiences gravitational acceleration, which provides additional shear to the system and thus eases a transition to the ultimate regime by relatively low Rayleigh numbers. In Z. Yao, M. S. Emran, A. Teimurazov, and O. Shishkina, Int. J. Heat Mass Transfer 236, 126314 (2025), DNS of centrifugal convection were conducted for a range of Rayleigh numbers between 2 × 105 ≤ Ra ≤ 8.88 × 108 and Froude numbers 0 ≤ Fr ≤ 100. In the setup we consider a vertically aligned cylindrical annulus with top and bottom solid walls, and cooled inner and heated outer sidewalls, all subject to a constant rotation around the vertical axis of the annulus (see figure below). For a fixed Ra (thermal driving) and increasing Fr (centrifugal driving), the global flow structure and heat transport scaling properties undergo a transition from those typical for vertical convection, where the imposed temperature gradient is orthogonal to the driving force (gravitational buoyancy), to those typical for Rayleigh–B´enard convection, where the temperature gradient is parallel to the force (centrifugal buoyancy). With increasing centrifugal buoyancy, the flow undergoes a transition from a three-dimensional global flow structure to a quasitwo-dimensional one, which is characterized by a suppressed mixing in the vertical direction. For larger Ra values, larger values of Fr are required for the transition.