Ultimate regime in Rayleigh–Bénard convection: The role of plates

The ultimate regime of convection, long ago predicted by Kraichnan [Phys. Fluids 5, 1374 (1962)], could be called elusive because some apparently equivalent experiments showed it while others did not, with no apparent reasons for this discrepancy. In this paper, we propose a model which accounts for the finite heat conductivity and heat capacity of real active boundaries. Bad thermal characteristics of the plates can explain differences between various experiments, in agreement with recent numerical simulations.