Ultimate Regime of Convection: robustness to poor thermal properties of the plates

TL;DR

This study tests a model predicting the impact of plate thermal properties on convection regimes, finding that the transition to the ultimate regime occurs regardless of plate conductivity, challenging the model's assumptions.

Contribution

The paper provides an experimental test of a phenomenological model linking plate thermal properties to convection regime transitions, revealing discrepancies with the model's predictions.

Findings

Transition to ultimate regime occurs with low conductivity plates.

Model predictions do not match experimental results.

Plate thermal properties have limited influence on the transition.

Abstract

A transition to Kraichnan ultimate regime of convection has been reported in very high Rayleigh numbers experiments, but not in all of them. These apparently contradictory results can be explained by a recent phenomenological model which accounts for the non-ideality of the plate thermal properties [Chill\`{a} et al, Physics of Fluids 16:2452 (2004)]. In this paper, we present a direct test of this model, using a low conductivity plate. We found an unaltered transition, not compatible with the model's predictions.