Heat-transport scaling and transition in geostrophic rotating convection with varying aspect ratio

Abstract

High-precision experimental and numerical data reveal that the power-law scaling (Nu $\ensuremath{\sim}$ Ra${}^{\ensuremath{\gamma}}$) of heat transport by geostrophic convection depends strongly on the fluid domain aspect ratio. Contrary to general belief, the data show that the very steep power-law scaling near onset ($\ensuremath{\gamma}\ensuremath{\ge}3$), does not exist in realistic experimental systems, owing to enhanced heat transfer by boundary flows formed near the lateral boundary. These results imply that the scaling relationship of heat transport measured in rotating convection cells with finite aspect ratio cannot be extrapolated to most large-scale, laterally unbounded, geophysical and astrophysical flows.