Salinity transfer in bounded double diffusive convection

TL;DR

This study numerically investigates salinity transfer in bounded double diffusive convection, comparing results with experiments and applying the Grossmann-Lohse theory to predict fluxes without new coefficients.

Contribution

It provides a detailed numerical analysis of salinity transfer in double diffusive convection and validates the Grossmann-Lohse theory for this specific flow.

Findings

Numerical results agree with experiments on salinity flux.

Salt fingers are present throughout the entire height of the flow.

The thermal Rayleigh number influences flow morphology but not salinity flux.

Abstract

The double diffusive convection between two parallel plates is numerically studied for a series of parameters. The flow is driven by the salinity difference and stabilized by the thermal field. Our simulations are directly compared to experiments by Hage and Tilgner (\emph{Phys. Fluids} 22, 076603 (2010)) for several sets of parameters and reasonable agreement is found. This in particular holds for the salinity flux and its dependence on the salinity Rayleigh number. Salt fingers are present in all simulations and extend through the entire height. The thermal Rayleigh number seems to have minor influence on salinity flux but affects the Reynolds number and the morphology of the flow. Next to the numerical calculation, we apply the Grossmann-Lohse theory for Rayleigh-B\'{e}nard flow to the current problem without introducing any new coefficients. The theory successfully predicts the salinity flux both with respect to the scaling and even with respect to the absolute value for the numerical and experimental results.