Enhanced heat transport in thermal convection with suspensions of rod-like expandable particles

Hu, Shi-Yuan and Wang, Kai-Zhe and Jia, Lai-Bing and Zhong, Jin-Qiang and Zhang, Jun (2021) Enhanced heat transport in thermal convection with suspensions of rod-like expandable particles. Journal of Fluid Mechanics, 928. R1. ISSN 1469-7645 (https://doi.org/10.1017/jfm.2021.809)

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Abstract

Thermal convection of fluid is a more efficient way than diffusion to carry heat from hot sources to cold places. Here, we experimentally study the Rayleigh–Bénard convection of aqueous glycerol solution in a cubic cell with suspensions of rod-like particles made of polydimethylsiloxane. The particles are inertial due to their large thermal expansion coefficient and finite sizes. The thermal expansion coefficient of the particles is three times larger than that of the background fluid. This contrast makes the suspended particles lighter than the local fluid in hot regions and heavier in cold regions. The heat transport is enhanced at relatively large Rayleigh number ( Ra ) but reduced at small Ra . We demonstrate that the increase of Nusselt number arises from the particle–boundary layer interactions: the particles act as ‘active’ mixers of the flow and temperature fields across the boundary layers.

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