On the thermal offset in turbulent rotating convection

A simple mechanistic model to explain the thermal offset observed in highly turbulent rotating convection experiments is presented. The experiments in dicate that for sufficiently high Taylor number the system develops an asym metry that is counter to the expected behavior of a Boussinesq fluid: The t emperature at the midplane of the experiment is higher than the average of the top and bottom isothermal boundaries. The magnitude of this bias increa ses with the basic rotation and with the density difference between the top and bottom boundaries. Our model considers this to be a result of a mean c irculation induced by centrifugal buoyancy. An analytical calculation of th is motion field, postulated to be a laminar perturbation to the turbulence- induced mean stratification, generates a reasonably accurate description of the observed thermal offset. (C) 1999 American Institute of Physics. [S107 0-6631(99)03508-4].