Non-Boussinesq effect: Thermal convection with broken symmetry

Jun Zhang, Stephen Childress, Albert Libchaber

Research output: Contribution to journalArticlepeer-review


We investigate large Rayleigh number (106-109) and large Prandtl number (102-103) thermal convection in glycerol in an aspect ration one cubic cell. The kinematic viscosity of the fluid strongly depends upon the temperature. The symmetry between the top and bottom boundary layers is thus broken, the so-called non-Boussinesq regime. In a previous paper Wu and Libchaber have proposed that in such a state the two thermal boundary layers adjust their length scales so that the mean hot and cold temperature fluctuations are equal in the center of the cell. We confirm this equality. A simplified two-dimensional model for the mean center temperature based on an equation for the thermal boundary layer is presented and compared with the experimental results. The conclusion is that the central temperature adjusts itself so that heat fluxes from boundaries are equal, temperature fluctuations at the center symmetrical, at a cost of very different temperature drops and Rayleigh number for each boundary.

Original languageEnglish (US)
Pages (from-to)1034-1042
Number of pages9
JournalPhysics of Fluids
Issue number4
StatePublished - Apr 1997

ASJC Scopus subject areas

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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