Transport near a vertical ice surface melting in water of various salinity levels

Abstract

The results of an experimental investigation of the buoyancy driven flow adjacent to a vertical ice surface melting in saline water are presented. Several ambient water salinities, s ∞ , are studied, namely 14‰, 17‰, 22‰, 30‰ and 35‰. For each salinity level, several ambient water temperatures, t ∞ , are investigated, ranging from t ∞ = − 1.75 °C when s ∞ = 35‰ to t ∞ = 17 °C when s ∞ = 17‰. Time exposure photographs of the flow field show that several distinctively different regimes of flow occur, depending on both the ambient water salinity level and temperature. At all of the salinities considered in the present study, the flow is observed to be laminar at low ambient water temperatures. This laminar flow is either upward, at the low salinity levels, or bi-directional at the higher salinities. At intermediate ambient water temperatures the flow is observed to be bi-directional and laminar over the lower portion of the ice surface, and upward and turbulent over the top portion of the ice surface. As the ambient water temperature is further increased the flow is seen to split, with a downward moving turbulent layer over the low er portion of the ice surface, and an upward moving layer over the top portion. The complicated nature of this type of flowis due to the interaction of two buoyancy force components, namely that due to salinity gradients and that due to thermal gradients. These forces are aiding or opposing, depending on the ambient water salinity level and temperature. Also, each of these forces exerts itself across a different thickness of the total boundary region. Velocity profiles, measured from the time exposure photographs, are presented and shown to be in good agreement with the analytical results of Carey and Gebhart [1, J. Fluid Mech. 107, 37–55 (1981)]. Measured solid-liquid interface temperatures and inferred interface salinities are also presented for the different salinity levels and ambient water temperatures.