Turbulent Rayleigh-Benard convection with polymers: Understanding how heat flux is modified
Publication in refereed journal

香港中文大學研究人員
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摘要We study how polymers affect the heat flux in turbulent Rayleigh-Benard convection at moderate Rayleigh numbers using direct numerical simulations with polymers of different relaxation times. We find that heat flux is enhanced by polymers and the amount of heat enhancement first increases and then decreases with the Weissenberg number, which is the ratio of the polymer relaxation time to the typical time scale of the flow. We show that this nonmonotonic behavior of the heat flux enhancement is the combined effect of the decrease in the viscous energy dissipation rate due to the viscosity of the Newtonian fluid and the increase in the energy dissipation rate due to polymers when Weissenberg number is increased. We explain why the viscous energy dissipation rate decreases with the Weissenberg number. Then by carrying out a generalized boundary layer analysis supplemented by a space-dependent effective viscosity from the numerical simulations, we provide a theoretical understanding of the change of the heat flux when the viscous energy dissipation rate is held constant. Our analysis thus provides a physical way to understand the numerical results.
著者Benzi R, Ching ESC, De Angelis E
期刊名稱Physical Review E
出版年份2016
月份12
日期21
卷號94
期次6
出版社AMER PHYSICAL SOC
國際標準期刊號2470-0045
電子國際標準期刊號2470-0053
語言英式英語
Web of Science 學科類別Physics, Fluids & Plasmas;Physics, Mathematical;Physics

上次更新時間 2020-16-10 於 03:26