Effect of surface roughness on heat transfer in Rayleigh-Bénard convection

Mark J. Tummers, Martin Steunebrink

Research output: Contribution to journalArticleScientificpeer-review

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This paper reports on an experimental study of the effects of surface roughness on the flow and heat transfer in cubical Rayleigh-Bénard convection cells for Rayleigh numbers between 107 and 1010. In the rough cells the top and bottom surfaces are equipped with square arrays of copper cubes. In line with other studies, three different regimes occur in the rough cells, with each regime having a different relation between the Nusselt number, Nu, and the Rayleigh number, Ra. In the first regime the Nu-Ra relation equals that of the smooth cell, but in the second and third regimes the Nu-Ra relation deviates from that of the smooth cell with significantly higher Nusselt numbers. To better understand these observations, the flow and temperature fields in both the smooth and rough cells were visualised by using particle image velocimetry with suspended thermochromic liquid crystals as flow tracer particles.

Original languageEnglish
Pages (from-to)1056-1064
JournalInternational Journal of Heat and Mass Transfer
Publication statusPublished - 2019


  • Heat transfer enhancement
  • Natural convection
  • Particle image velocimetry
  • Rayleigh-Bénard convection
  • Surface roughness
  • Thermochromic liquid crystals

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