Salt Finger Fluxes in a Laminar Shear Flow

This dissertation presents an experimental study of the buoyancy fluxes produced by salt fingers in the presence of a laminar shear flow. An annular tank was used in the experiments. Sugar and salt were used as the diffusing components. Salt fingers, initially aligned in the vertical, were observed to tilt when the shear flow was imposed. The fingers were also observed to be 3-dimensional structures at all times during the experiments. A consistent decrease in the salt fluxes was measured as the the Reynolds number was increase by increasing the shear velocity magnitudes. Through a regression analysis, the salt fluxes were found to depend upon the Reynolds number as powers given by -0.025, -0.1 and -0.34, when the density ratio was equal to 1.2, 1.54 and 2.1 respectively. A polynomial expression that encompasses the dependence of the salt fluxes with Reynolds number and density ratio is also suggested. A linear stability theory for fingers tilted by a shear flow together with a flux reduction mechanism, proposed by Krishnamurti (personal communication), are suggested as possible explanations for the experimental results.