Abstract

Many environmental flows arise due to natural convection at a vertical surface, from flows in buildings to dissolving ice faces at marine-terminating glaciers. We use three-dimensional direct numerical simulations of a vertical channel with differentially heated walls to investigate such convective, turbulent boundary layers. Through the implementation of a multiple-resolution technique, we can perform simulations at a wide range of Prandtl numbers. We determine how the heat flux, wall shear, and Reynolds number depend on the Prandtl number, and identify the key role of thin, conductive sublayers in controlling these quantities. Finally, we also consider the passive transport of temperature in salt-driven vertical convection, the role of differential diffusion, and the implications of our results for the parameterisation of heat and salt fluxes at ice-ocean interfaces.