Turbulent convection at high Rayleigh numbers and aspect ratio 4

J. J. Niemela, K. R. Sreenivasan

Research output: Contribution to journalArticlepeer-review


We report measurements of the Nusselt number, Nu, in turbulent thermal convection in a cylindrical container of aspect ratio 4. The highest Rayleigh number achieved was Ra = 2 × 1013. Except for the last half a decade or so of Ra, experimental conditions obey the Boussinesq approximation accurately. For these conditions, the data show that the log Nu-log Ra slope saturates at a value close to 1/3, as observed previously by us in experiments with smaller aspect ratios. The increasing slope over the last half a decade of Ra is inconclusive because the corresponding conditions are non-Boussinesq. Finally, we report a modified scaling relation between the plume advection frequency and Ra that collapses data for different aspect ratios.

Original languageEnglish (US)
Pages (from-to)411-422
Number of pages12
JournalJournal of Fluid Mechanics
StatePublished - Jun 25 2006

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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