Salt fingers at low Rayleigh numbers

Abstract

This is a laboratory study of salt fingers at low Rayleigh numbers. We report on the stability boundary in the (RS, RT)-plane (where RS and RT are the salt and heat Rayleigh numbers respectively), the wavenumber of the observed fingers, and the planform. In this low RS, RT range, fingers have width comparable to their height, as predicted by linear stability theory. The planform appears to be close-packed polygonal cells when they are formed on curved profiles of temperature and salinity. However, the planform is distinctly rolls when care is taken to approximate linear profiles.