Two-fluid single-column modelling of Rayleigh-B\'{e}nard convection as a step towards multi-fluid modelling of atmospheric convection

TL;DR

This paper develops a simple two-fluid single-column model for Rayleigh-Bénard convection, demonstrating it can accurately predict heat flux scaling over a wide range of buoyancy forcing, advancing multi-fluid atmospheric convection modeling.

Contribution

It introduces a minimal two-fluid model that captures key convection dynamics without complex closures, aiding the development of multi-fluid atmospheric models.

Findings

Accurately predicts heat flux scaling over six orders of magnitude of Rayleigh number.

Shows simple two-fluid models can capture dominant convection structures.

Supports the potential of multi-fluid approaches in atmospheric convection modeling.

Abstract

Multi-fluid models have recently been proposed as an approach to improving the representation of convection in weather and climate models. This is an attractive framework as it is fundamentally dynamical, removing some of the assumptions of mass-flux convection schemes which are invalid at current model resolutions. However, it is still not understood how best to close the multi-fluid equations for atmospheric convection. In this paper we develop a simple two-fluid, single-column model with one rising and one falling fluid. No further modelling of sub-filter variability is included. We then apply this model to Rayleigh-B\'{e}nard convection, showing that, with minimal closures, the correct scaling of the heat flux (Nu) is predicted over six orders of magnitude of buoyancy forcing (Ra). This suggests that even a very simple two-fluid model can accurately capture the dominant coherent overturning structures of convection.