Particle image velocimetry investigation of void seepage through a simulated ice jam
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Date
2020
Authors
Murray, Andrew
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Abstract
Many rivers in cold climate regions can experience ice jams, which can be significant contributors to heavy flooding, especially when coinciding with higher spring runoff flows. Due to the danger and unpredictability inherent with ice jams, laboratory studies are often used to analyse flow conditions underneath ice jams. An experiment was conducted in the small-scale Particle Image Velocimetry (PIV) flume at the University of Manitoba, using polyethylene pellets to simulate the accumulation of ice pieces in a breakup ice jam. The goals of this experiment were to examine the flow conditions under a simulated ice jam using PIV, and develop a methodology for calculating void seepage, the portion of total river flow within the jam. Contours and profiles were presented for average velocities and turbulence statistics for three test conditions at a constant Froude number and varied upstream water depths of 5, 10, and 15 cm. Velocity profiles were integrated to calculate void seepage along the jam, with the percentage of seepage then related to the relative thickness of the ice jam. Seepage values were found to be often near 5% of total flume discharge, reaching as high as 14% at the thickest portions of the ice jam. A cubic polynomial was fitted to the dataset relating the recorded seepage ratios to the relative jam thickness. The recorded seepage flow and estimated hydraulic gradient was also used to calculate a minimum seepage velocity parameter for the model ice jam, found to be λ = 0.57 m/s.
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Keywords
Particle image velocimetry, Ice jam, Hydraulics, River ice