Turbulent rotating rayleigh-benard convection: Spatiotemporal and statistical study

The present study involves a 3D numerical investigation of rotating Rayleigh-Benard convection in a large aspect-ratio (8:8:1) rectangular enclosure. The rectangular cavity is rotated about a vertical axis passing through the center of the cavity. The governing equations of mass, momentum, and energy for a frame rotating with the enclosure, subject to generalized Boussinesq approximation applied to the body and centrifugal force terms, have been solved on a collocated grid using a semi-implicit finite difference technique. The simulations have been carried out for liquid metal flows having a fixed Prandtl number Pr=0.01 and fixed Rayleigh number Ra=10⁷ while rotational Rayleigh number Ra_w and Taylor number Ta are varied through nondimensional rotation rate (ω) ranging from 0 to 104. Generation of large-scale structures is observed at low-rotation (ω=10) rates though at higher-rotation rates (ω=10⁴) the increase in magnitude of Coriolis forces leads to redistribution of buoyancy-induced vertical kinetic energy to horizontal kinetic energy. This brings about inhibition of vertical fluid transport, thereby leading to reduced vertical heat transfer. The magnitude of rms velocities remains unaffected with an increase in Coriolis forces from ω=0 to 10⁴. An increase in rotational buoyancy (Ra_w), at constant rotation rate (ω=10⁴), on variation in Ra_w/Ta from 10^-3 to 10^-2 results in enhanced breakup of large-scale structures with a consequent decrease in rms velocities but with negligible reduction in vertical heat transport.