Heat transport in liquid metal convection from onset to turbulence: the effect of small aspect ratio

Ren, Lei1; Tao, Xin1; Zhang, Lu2,3; Xia, Ke-Qing2,3,4; Xie, Yi-Chao1

2024-09-13

10.1017/jfm.2024.630

JOURNAL OF FLUID MECHANICS   影响因子和分区

0022-1120

1469-7645

We present a systematic study on the effects of small aspect ratios Gamma on heat transport in liquid metal convection with a Prandtl number of Pr = 0.029. The study covers 1/20 <= Gamma <= 1 experimentally and 1/50 <= Gamma <= 1 numerically, and a Rayleigh number Ra range of 4 x 10(3) <= Ra <= 7 x 10(9). It is found experimentally that the local effective heat transport scaling exponent. changes with both Ra and Gamma, attaining a Gamma -dependent maximum value before transition-to-turbulence and approaches gamma = 0.25 in the turbulence state as Ra increases. Just above the onset of convection, Shishkina (Phys. Rev. Fluids, vol 6, 2021, 090502) derived a length scale l = H/(1 + 1.49 Gamma(-2))(1/3). Our numerical study shows Ra-l, i.e. Ra based on l, serves as a proper control parameter for heat transport above the onset with Nu - 1 = 0.018(1 + 0.34/ Gamma 2)(Ra/Ra-c,Ra- Gamma - 1). Here Ra-c,Ra- Gamma represents the Gamma-dependent critical Ra for the onset of convection and Nu is the Nusselt number. In the turbulent state, for a general scaling law of Nu - 1 similar to Ra-alpha, we propose a length scale l = H/(1 + 1.49 Gamma(-2))(1/[3(1-alpha)]). In the case of turbulent liquid metal convection with a = 1/4, our measurement shows that the heat transport will become weakly dependent on Gamma with Ra-l = Ra/(1 + 1.49 Gamma(-2)4/3) >= 7 x 10(5). Finally, once the flow becomes time-dependent, the growth rate of Nu with Ra declines compared with the linear growth rate in the convection state. A hysteresis is observed in a Gamma = 1/3 cell when the flow becomes time-dependent. Measurements of the large-scale circulation suggest the

Benard convection turbulent convection

SCI

英语

其他

National Science Foundation of China["92152104","12072144","12232010","12202173"]

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:001310660500001

CAMBRIDGE UNIV PRESS

Web of Science

1.Xi An Jiao Tong Univ, Sch Aerosp, State Key Lab Strength & Vibrat Mech Struct, Xian 710049, Peoples R China
2.Southern Univ Sci & Technol, Ctr Complex Flows & Soft Matter Res, Shenzhen 518055, Peoples R China
3.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen 518055, Peoples R China
4.Southern Univ Sci & Technol, Dept Phys, Shenzhen 518055, Peoples R China

Ren, Lei,Tao, Xin,Zhang, Lu,et al. Heat transport in liquid metal convection from onset to turbulence: the effect of small aspect ratio[J]. JOURNAL OF FLUID MECHANICS,2024,993.

Ren, Lei,Tao, Xin,Zhang, Lu,Xia, Ke-Qing,&Xie, Yi-Chao.(2024).Heat transport in liquid metal convection from onset to turbulence: the effect of small aspect ratio.JOURNAL OF FLUID MECHANICS,993.

Ren, Lei,et al."Heat transport in liquid metal convection from onset to turbulence: the effect of small aspect ratio".JOURNAL OF FLUID MECHANICS 993(2024).