Frazil evolution in channels

Frazil dynamics and precipitation in a water column with depth-dependent supercooling

“…This can have important consequences in studies predicting the location of frazil precipitation. In practice, these findings suggest that all initial frazil should be put into one size class (as in the study of Hammar & Shen 1995) unless there is a good reason to do otherwise.…”

“…The heat flux from a growing frazil crystal is given by 16) where Nu = 1 is the Nusselt number (SJ), K T = 1.4 × 10 −7 m 2 s −1 is the molecular thermal diffusivity, the disk radius is used as the appropriate length scale for calculating the temperature gradient (Hammar & Shen 1995) and 2πr i t i is the surface area of the disk edge. Growth of frazil crystals is assumed to occur only at the disk edges because experiments have shown that the growth rate in the direction of the ice crystal a-axis is 1-2 orders of magnitude larger than the growth rate in the c-axis direction (Daly 1994b); the growth in the a-axis direction is limited primarily by the diffusion of latent heat or salt while growth of c-axis faces is limited by the attachment rate of water molecules to the ice surface.…”

A test of common assumptions used to infer subglacial water flow through overdeepenings

“…This suspended ice then accretes to the glacier sole or the underlying substrate as anchor ice (e.g. Svensson and Omstedt, 1994;Hammar and Shen, 1995;Cook and others, 2006). Faster-flowing water will be warmed by viscous heating and will require greater cooling before frazil ice begins to form.…”

Numerical model of frazil ice and suspended sediment concentrations and formation of sediment laden ice in the Kara Sea

“…Disks that are initially small and tend not to stick to sediment particles during collisions evolve into large complex aggregates that are capable of sweeping up sediment particles along their rising path [Reimnitz et al, 1993a;Kempema et al, 1993]. Treatment of changes in particle populations and characteristics is clearly required to model correctly the ice-ice, sedimentsediment, and ice-sediment interactions, and progress toward this capability has been made for sediment [e.g., Hill and Nowell, 1995] and for ice [Svensson and Omstedt, 1994;1998;Hammar and Shen, 1995]. However, the correct treatment involves a substantial increase in the complexity of the model and requires tracking the concentration, size, density, and settling velocity of the evolving particle population and new model parameters to describe aggregation efficiency and relate size with density and settling velocity [Hammar and Shen, 1995;Hill and Nowell, 1995].…”

“…Treatment of changes in particle populations and characteristics is clearly required to model correctly the ice-ice, sedimentsediment, and ice-sediment interactions, and progress toward this capability has been made for sediment [e.g., Hill and Nowell, 1995] and for ice [Svensson and Omstedt, 1994;1998;Hammar and Shen, 1995]. However, the correct treatment involves a substantial increase in the complexity of the model and requires tracking the concentration, size, density, and settling velocity of the evolving particle population and new model parameters to describe aggregation efficiency and relate size with density and settling velocity [Hammar and Shen, 1995;Hill and Nowell, 1995]. Only a handful of measurements have been performed to provide empirical guidance for these parameters [Carstens, 1966;Kempema et al, 1989;Ackermann et al, 1994;Lindemann and Smedsrud, 1998].…”