Diapycnal mixing efficiency in lock-exchange gravity currents

An experimental measure of irreversible mixing efficiency, $R\phantom{\rule{0}{0ex}}{i}_{f}^{*}$, for a lock-exchange gravity current is presented. The results show that mixing efficiency increases and is sustained in the presence of strong stratification provided the flow energy is high. Following this, various turbulence regimes are mapped based on turbulent Froude number and turbulent Reynolds number. Additionally, $R\phantom{\rule{0}{0ex}}{i}_{f}^{*}$ is shown to have a strong dependence on turbulence regime and molecular effects induced by Prandtl number.