Flow reversals in Rayleigh-Benard convection with non-Oberbeck-Boussinesq effects

Shuning Xia University of Science and Technology of China Zhenhua Wan University of Science and Technology of China Shuang Liu University of Science and Technology of China Qi Wang University of Science and Technology of China Dejun Sun University of Science and Technology of China

Fluid Dynamics and Shock Waves mathscidoc:2205.14003

Journal of Fluid Mechanics, 798, 2016.7
Flow reversals in two-dimensional Rayleigh-Benard convection led by non-Oberbeck-Boussinesq (NOB) effects due to large temperature differences arc studied by direct numerical simulation. Perfect gas is chosen as the working fluid and the Prandtl number is 0.71 for the reference state. 11 NOB effects are included, the flow pattern P-11 with only one dominant roll often becomes unstable by the growth of the cold corner roll, which sometimes results in cession-led flow reversals. By exploiting the vorticity transport equation, it is found that the asymmetries of buoyancy and viscous forces are responsible for the growth of the cold corner roll because both such asymmetries cause an imbalance between the corner rolls and the large-scale circulation (I.SC). The buoyancy force near the cold wall increases and decreases near the hot wall originating from the temperature-dependent isobaric thermal expansion coefficient alpha = 1/T if NOB effects are included; Moreover, the decreased dissipation due to lower viscosity is favourable for the growth of the cold corner roll, while the increased viscosity further suppresses the growth of the hot corner roll. Finally, it is found that the boundary layer near the cold wall plays an important role in the mass transport from LSC to corner rolls subject to mass conservation.
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@inproceedings{shuning2016flow,
  title={Flow reversals in Rayleigh-Benard convection with non-Oberbeck-Boussinesq effects},
  author={Shuning Xia, Zhenhua Wan, Shuang Liu, Qi Wang, and Dejun Sun},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20220517141738665135217},
  booktitle={Journal of Fluid Mechanics},
  volume={798},
  year={2016},
}
Shuning Xia, Zhenhua Wan, Shuang Liu, Qi Wang, and Dejun Sun. Flow reversals in Rayleigh-Benard convection with non-Oberbeck-Boussinesq effects. 2016. Vol. 798. In Journal of Fluid Mechanics. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20220517141738665135217.
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