Formation and movement of ice accumulation waves under ice cover –an experimental study

Abstract

Ice jams in rivers often arise from the movement of frazil ice as cover-load under ice cover, a process which is conceptually similar to the movement of sediment as bed-load along a river bed. The formation and movement of an ice-accumulation wave is one facet of a larger class of cover-load movements. The movement of an ice-accumulation wave obviously plays a crucial role in the overall process of ice accumulation. In the present study, experiments under different flow and ice conditions help reveal the mechanics of formation and evolution of ice-accumulation waves. In particular, suitable criteria for formation of an ice-accumulation wave are investigated along with the resulting speed of wave propagation. The transport capacity of frazil ice under waved accumulation is modeled by comparing those of experiments collected in laboratories, and the resulting equation is shown to be in good agreement with measured experimental results.

Impact of Local Scour around a Bridge Pier on Migration of Waved-Shape Accumulation of Ice Particles under an Ice Cover

“…The comparison between the calculated results and those of experiments is shown in Table 2. In Table 2, the wave crest thickness with the presence of the local scour in the bed is calculated by Equation ( 13), and the wave crest thickness without the presence of the local scour is calculated by the formula proposed by Wang et al [34]. As shown in Table 2, the calculated results agree well with those of experiments.…”

“…In this study, the flow Froude number was used as an important factor for describing the flow intensity relevant for the accumulation process of an ice jam. Thus, when the flow Froude number is more than the critical Froude number for the development of an ice jam, frazil ice particles cannot accumulate under an ice cover, but will be washed out and transported to the downstream section of the channel, referred as to the "wash-load" [34]. To investigate the impact of the scour hole on the migration of ice waves, flow conditions for all experimental runs were controlled with the flow Froude number less than its critical value.…”

“…As shown in Figure 3, during the migration process of an ice wave, along the flow direction, points "A", "B", and "C" represent the "wave starting point", "wave crest", and "wave trough" of an ice wave, respectively. The A-B section is the stoss side of an ice wave, and the B,C section is the lee side of an ice wave [34]. The appearance of ice waves under an ice jam creates extra resistance to the flowing water.…”

“…Regarding the influence of the thickness of an ice wave on the depth of the scour hole, according to Wang et al [34], the thicker the ice jam, the deeper the scour hole, and thus, the higher risk to the pier. Under the action of an ice wave, a channel reach from the upstream ice jam head (or wave front or free water surface) to the pier is considered the study "control volume".…”

Analytical Models of Velocity, Reynolds Stress and Turbulence Intensity in Ice-Covered Channels

“…The ice sheet in some Canadian rivers is at least 0.6 m thick and lasts for at least 4 months [1]. The wetted perimeter of the cross section and flow resistance in ice-covered flows increases with the presence of the ice sheet, which significantly affects the hydraulic characteristics of river and topographical features and greatly change the flow velocity distribution, flow transport capacity and sediment transport rate [2][3][4][5][6][7][8][9][10][11]. Therefore, it is necessary to study the ice-covered flows.…”