78th Annual Meeting of the APS Division of Fluid Dynamics (Nov 23 — 25, 2025)

P009: Boundary-layer sweeping by a self-propelled rotor in Rayleigh-Bénard convection

Authors
  • Jin-Qiang Zhong, Tongji University
  • Ying-Rui Wang , Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
  • Xin Dong , Department of Aeronautics and Astronautics, Fudan University, Shanghai, China
  • Jun Zhang , NYU - ECNU Institute of Physics, New York University Shanghai, Shanghai, China

Shadowgraph images (sideview) show close interactions between a self-propelled rigid rotor and the thermal plumes / boundary layers in Rayleigh-Bénard convection. The experiment is performed in a horizontal cylindrical cell of diameter D = 25.0 cm and length L = 12.5 cm. The working fluid is 50 wt% aqueous solution of glycerin with Pr = 42.6 and Ra = 4.7×108 . The rotor, which consists of eight Plexiglas blades, is driven by the convective flows and sustains steady rotation about the central axis of the cylinder. As the blades pass by, their tips invade and sweep the thermal boundary layers, promoting the emissions of new thermal plumes and rectifying the turbulent flows. Such fluid-structure interaction significantly enhances the plume velocity as well as the global heat transport in turbulent thermal convection.

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