Heat transport and flow morphology of geostrophic rotating Rayleigh-Benard convection in the presence of boundary flow

Ding, Guang-Yu1,2,3; Xia, Ke-Qing1,2

2023-11-22

10.1017/jfm.2023.872

JOURNAL OF FLUID MECHANICS   影响因子和分区

0022-1120

1469-7645

Using direct numerical simulations, we investigate the heat transport in bulk and boundary flows separately in rotating Rayleigh-Benard convection in cylindrical cells. In the bulk we observe a steep scaling relationship between the Nusselt number (Nu) and the Rayleigh number (Ra), which is consistent with the results from simulations using periodic boundary conditions. For the boundary flow, we observe a power law Nu(BF) similar to (Ra/Ra-w)(1) at the leading order, where Nu(BF) is the local Nusselt number of the boundary flow and Ra-w is the onset Rayleigh number of the wall mode. We develop a model using the boundary layer marginal stability theory to explain this power law, and further show that a more precise description of the data can be obtained if a higher-order correction is introduced. A striking finding of our study is the observation of a sharp transition in flow state, manifested by a sudden drop in Nu(BF) with a corresponding collapse of the boundary flow coherency. After the transition, the boundary flow breaks into vortices, leading to a reduction in flow coherency and heat transport efficiency. As the physical properties of the vortices should not depend on the aspect ratio, Nu(BF) for all aspect ratios collapse together after the transition. Moreover, the centrifugal force helps trigger the breakdown of the coherent boundary flow state. For this reason, Nu(BF) for the cases with non-zero centrifugal force collapse together. We further develop a method that enables us to separate the contributions from the bulk and boundary flows in the global Nusselt number using only the global Nu and it does not require the centrifugal force to be absent.

rotating flows Benard convection turbulent convection

SCI ; EI

英语

第一 ; 通讯

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:001105695500001

CAMBRIDGE UNIV PRESS

20235115258764

Aspect ratio ; Boundary layers ; Morphology ; Natural convection ; Vortex flow

Fluid Flow, General:631.1 ; Heat Transfer:641.2 ; Physical Properties of Gases, Liquids and Solids:931.2 ; Materials Science:951

ENGINEERING

Web of Science

1.Southern Univ Sci & Technol, Ctr Complex Flows & Soft Matter Res, Shenzhen 518055, Peoples R China
2.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen 518055, Peoples R China
3.Chinese Univ Hong Kong, Dept Phys, Hong Kong, Peoples R China

Ding, Guang-Yu,Xia, Ke-Qing. Heat transport and flow morphology of geostrophic rotating Rayleigh-Benard convection in the presence of boundary flow[J]. JOURNAL OF FLUID MECHANICS,2023,975.

Ding, Guang-Yu,&Xia, Ke-Qing.(2023).Heat transport and flow morphology of geostrophic rotating Rayleigh-Benard convection in the presence of boundary flow.JOURNAL OF FLUID MECHANICS,975.

Ding, Guang-Yu,et al."Heat transport and flow morphology of geostrophic rotating Rayleigh-Benard convection in the presence of boundary flow".JOURNAL OF FLUID MECHANICS 975(2023).