Finite-size effects lead to supercritical bifurcations in turbulent rotating Rayleigh-Bénard convection

Stephan Weiss, Richard Johannes Antonius Maria Stevens, Jin-Qiang Zhong, H.J.H. Clercx, Detlef Lohse, Günter Ahlers

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Abstract

In turbulent thermal convection in cylindrical samples with an aspect ratio $\Gamma \equiv D/L$ ($D$ is the diameter and $L$ the height), the Nusselt number Nu is enhanced when the sample is rotated about its vertical axis because of the formation of Ekman vortices that extract additional fluid out of thermal boundary layers at the top and bottom. We show from experiments and direct numerical simulations that the enhancement occurs only above a bifurcation point at a critical inverse Rossby number 1/Ro$_c$, with 1/Ro$_c \propto 1/\Gamma$. We present a Ginzburg-Landau–like model that explains the existence of a bifurcation at finite 1/Ro$_c$ as a finite-size effect. The model yields the proportionality between 1/Ro$_c$ and $1/\Gamma$ and is consistent with several other measured or computed system properties.
Original languageUndefined
Pages (from-to)224501
Number of pages4
JournalPhysical review letters
Volume105
Issue number22
DOIs
Publication statusPublished - 2010

Keywords

  • EWI-19488
  • EC Grant Agreement nr.: FP6/031513
  • EC Grant Agreement nr.: FP7/222919
  • METIS-269535
  • IR-75849

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