2023/02/22 by Zhong, Jun, Wang, Dongpu, Sun, Chao · 1 citation
#FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn)
paper · doi:10.48550/arxiv.2302.11214
We investigate the coupling effect of buoyancy and shear based on an annular centrifugal Rayleigh-Bénard convection (ACRBC) system in which two cylinders rotate with an angular velocity difference. Direct numerical simulations are performed in a Rayleigh number range 106 ≤ Ra ≤ 108, at fixed Prandtl number Pr=4.3, inversed Rossby number Ro-1=20 and radius ratio η=0.5. The shear, represented by the non-dimensional rotational speed difference Ω, varies from 0 to 10, corresponding to an ACRBC without shear and a radially heated Taylor-Couette flow with only the inner cylinder rotating, respectively. A stable regime is found in the middle part of the interval of Ω, and divides the whole parameter space into three regimes: buoyancy-dominated regime, stable regime, and shear-dominated regime. Clear boundaries between the regimes are given by linear stability analysis. In the buoyancy-dominated regime, the flow is a quasi-two-dimensional flow on the rφplane; as shear increases, both the growth rate of instability and the heat transfer is depressed. In the shear-dominated regime, the flow is mainly on the rz plane, and the heat transfer in this regime is greatly enhanced. The study shows shear can stabilize buoyancy-driven convection and reveals the complex coupling mechanism of shear and buoyancy, which may have implications for fundamental studies and industrial designs.