Author(s): Chuankang Pei; Yuntong She; Mark Loewen
Linked Author(s): Mark R. Loewen, Yuntong She
Keywords: River ice; Frazil ice; Frazil floc; Flocculation process; Frazil properties
Abstract:
Frazil ice particles form in turbulent supercooled water and frazil flocs form by aggregation of frazil particles in the turbulent flow through the process of flocculation. Frazil flocs eventually become buoyant enough that they rise to the surface becoming frazil ice pans, contributing to the surface ice generation and ice cover formation. In this study, a series of laboratory experiments were performed in a frazil ice tank to investigate the correlation between frazil particle and floc properties under different air temperatures and turbulent dissipation rates to further our understanding of the frazil flocculation process. A high-resolution camera system was used to capture time-series images of frazil particles and flocs between two cross-polarising filters. Precision temperature recorders were used to monitor water and air temperatures. Time series of frazil particle and floc properties were obtained to analyze their correlations. Results show a strong linear relationship between particle and floc number concentrations with a floc-to-particle number concentration ratio ranging from 0.29~0.35. The ratio was not affected much by changing air temperature but was reduced by 12~17% at a lower turbulence dissipation rate. A moderate to strong nonlinear correlation was found between mean particle size and mean floc size described by an exponential relationship when particle mean sizes increased or decreased significantly. When particle mean size reaches an approximate equilibrium, a weak to moderate linear correlation was found between mean particle and floc size and the negative slope suggests they are inversely correlated.
Year: 2024