Salt fingers in double-diffusive systems

“Salt fingering”, the phenomenon of the double-diffusive convection has been studied experimentally. We prepared a system with vertical density variation, which contains salt and sugar solutions, separated one from the other. The “salt fingers” appear at the interface between these layers of salt and sugar solutions. The “salt fingers” have been observed by means of shadowgraph technique. With the aid of a computer and the video-capture technique, it was possible for the first time to conduct a detailed investigation of the phenomenon. The geometric characteristics of the “salt fingers” such as form, length and width have been investigated. The way in which these quantities depend on the salinity and sugar concentrations, as well as the thickness of the salt and sugar layers has been verified experimentally. We also verified the predicted form of dependence of the average “salt fingers” width on its vertical length.