Dynamical and statistical phenomena of circulation and heat transfer in periodically forced rotating turbulent Rayleigh-Bénard convection

Sebastian Sterl, Hui-Min Li, and Jin-Qiang Zhong
Phys. Rev. Fluids 1, 084401 – Published 27 December 2016

Abstract

In this paper, we present results from an experimental study into turbulent Rayleigh-Bénard convection forced externally by periodically modulated unidirectional rotation rates. We find that the azimuthal rotation velocity θ̇(t) and thermal amplitude δ(t) of the large-scale circulation (LSC) are modulated by the forcing, exhibiting a variety of dynamics including increasing phase delays and a resonant peak in the amplitude of θ̇(t). We also focus on the influence of modulated rotation rates on the frequency of occurrence η of stochastic cessation or reorientation events, and on the interplay between such events and the periodically modulated response of θ̇(t). Here we identify a mechanism by which η can be amplified by the modulated response, and these normally stochastic events can occur with high regularity. We provide a modeling framework that explains the observed amplitude and phase responses, and we extend this approach to make predictions for the occurrence of cessation events and the probability distributions of θ̇(t) and δ(t) during different phases of a modulation cycle, based on an adiabatic approach that treats each phase separately. Last, we show that such periodic forcing has consequences beyond influencing LSC dynamics, by investigating how it can modify the heat transport even under conditions where the Ekman pumping effect is predominant and strong enhancement of heat transport occurs. We identify phase and amplitude responses of the heat transport, and we show how increased modulations influence the average Nusselt number.

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  • Received 19 August 2016

DOI:https://doi.org/10.1103/PhysRevFluids.1.084401

©2016 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Fluid Dynamics

Authors & Affiliations

Sebastian Sterl1,2,*, Hui-Min Li1, and Jin-Qiang Zhong1,†

  • 1Fluid Lab, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
  • 2Physics of Fluids Group, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands

  • *Present address: NewClimate Institute for Climate Policy and Global Sustainability gGmbH, Am Hof 20-26, 50667 Cologne, Germany.
  • Corresponding author: jinqiang@tongji.edu.cn

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Issue

Vol. 1, Iss. 8 — December 2016

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