AN EXPERIMENTAL STUDY OF MELTING VERTICAL ICE CYLINDERS IN COLD WATER

Abstract

Short vertical ice cylinders were melted in quiescent ambient cold fresh water to visualize the melting and the resulting convective motions. Melting rates and heat transfer parameters were also determined. The cylinder penetrated the water surface, to model the melting of floating surface ice. Melting experiments over the ambient medium temperature range, t ∞, from 2 to 7°C covered the whole gamut of differing and complicated effects found to be associated with the occurance of a density extremum. At t ∞ = 2°C, simple general upflow is found, at t ∞ = 7°C simple downflow. Between these two limits, three different and much more complicated regimes arose. Buoyancy force reversal arises first, with increasing t ∞, at about 4°C. Then local flow reversal follows, in the range to about 5.3°C. Finally a convective inversion, that is, an average flow reversal, occurs. A tremendous variation of flow pattern occurs over a range of only a few degrees. Melting rates become very low in the region of inversion. This was also found in previous measurements with the simpler flows which occur adjacent to thin and completely submerged vertical ice slabs. However, many flow and transport effects were quite different, with a flat bottom surface and with the ice-water-air interface. Three flows of different configurations interact. It appears that the realistic modelling of the melting of multidimensional pieces of surface ice will require a composite of the different characteristics of these multiple regions.