Enhanced and reduced heat transport in turbulent thermal convection with polymer additives

Ping Wei, Rui Ni, Ke Qing Xia

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24 Scopus citations

Abstract

We present an experimental study of turbulent Rayleigh-Bénard convection with polymer additives made in two convection cells, one with a smooth top and bottom plates and the other with a rough top and bottom plates. For the cell with smooth plates, a reduction of the measured Nusselt number (Nu) was observed. Furthermore, the amount of Nu reduction increases with increasing polymer concentration (c), reaching ∼12% for c=120 ppm and an apparent leveling off thereafter. For the cell with rough plates, however, an enhancement (∼4%) of Nu was observed when the polymer concentration is greater than 120 ppm. This increase in Nu is corroborated by an increased large-scale circulation (LSC) velocity in the same cell when polymers are added. In contrast, the LSC velocity in the smooth cell is found to be essentially the same with and without polymers. It is further found that in the smooth cell the rms values of the global Nu, σ Nu , and that of the local temperature, σ T , both exhibit similar dependence on c as Nu itself. In contrast, σ Nu and σ T in the rough cell are found to be essentially independent of c.

Original languageEnglish (US)
Article number016325
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume86
Issue number1
DOIs
StatePublished - Jul 30 2012

All Science Journal Classification (ASJC) codes

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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