Transport and profile measurements of the diffusive interface in double diffusive convection with similar diffusivities

Abstract

The transport properties of a diffusive interface with diffusivity ratio $\kappa_S/\kappa_T = {\textstyle\frac{1}{3}}$ have been measured, using salt and sugar as the diffusing components. The flux ratio is constant and equal to (κ_S/κ_T)^½. The normalized salt flux is related to the density anomaly ratio R_ρ = βΔS/αΔT by the power law F*_T = 2·59R_ρ^−12.6 over four decades. Optical measurements show that the vertical gradients of concentration of salt and sugar within the interface are those required if molecular diffusion is to account for the whole flux of each component.