Azimuthal symmetry, flow dynamics, and heat transport in turbulent thermal convection in a cylinder with an aspect ratio of 0.5

Chao Sun, Heng Dong Xi, Ke Qing Xia

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

We report an experimental study of flow dynamics and structure in turbulent thermal convection. Flow visualization, together with particle image velocimetry (PIV) measurement, reveal that the instantaneous flow structure consists of an elliptical circulatory roll and two smaller counterrotating rolls, and that the azimuthal motion of the quasi-2D instantaneous flow structure produces a time-averaged 3D flow pattern featuring two toroidal rings near the top and bottom plates, respectively. The apparently stochastic azimuthal motion of the flow structure, which generates a net rotation on average, is found to possess the characters of a Brownian ratchet. Using an artificially generated flow mode, we are able to produce a bimodal-Nu behavior and thus demonstrate that different flow states can indeed produce different global heat transport in a turbulent convection system.

Original languageEnglish
Article number074502
JournalPhysical Review Letters
Volume95
Issue number7
DOIs
StatePublished - 12 Aug 2005
Externally publishedYes

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