Two-Scalar Turbulent Rayleigh-Benard Convection: Numerical Simulations and Unifying Theory

TL;DR

This paper presents numerical simulations of turbulent Rayleigh-Benard convection driven by two scalars with different diffusivities and extends the Grossmann-Lohse theory to predict fluxes and Reynolds number in such complex systems.

Contribution

The study generalizes the Grossmann-Lohse theory to two-scalar turbulent convection, successfully predicting fluxes and flow characteristics.

Findings

Generalized theory accurately predicts fluxes and Reynolds number.

Numerical simulations confirm the theory's effectiveness across parameters.

Extends the applicability of the Grossmann-Lohse theory to multi-scalar convection.

Abstract

We conduct direct numerical simulations for turbulent Rayleigh-B\'{e}nard (RB) convection, driven simultaneously by two scalar components (say, temperature and salt concentration) with different molecular diffusivities, and measure the respective fluxes and the Reynolds number. To account for the results, we generalize the Grossmann-Lohse theory for traditional RB convections~(Grossmann and Lohse, J. Fluid Mech., 407, 27-56; Phys. Rev. Lett., 86, 3316-3319; Stevens et al., J. Fluid Mech., 730, 295-308) to this two-scalar turbulent convection. Our numerical results suggest that the generalized theory can successfully predict the overall trends for the fluxes of two scalars and the Reynolds number. In fact, for most of the parameters explored here, the theory can even predict the absolute values of the fluxes and the Reynolds number with good accuracy. The current study extends the generality of the Grossmann-Lohse theory in the area of the buoyancy-driven convection flows.