Item: High-speed video recording in snow chute experiments
Title: High-speed video recording in snow chute experiments
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Marius Schaefer∗,a, Martin Kernb aWSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland bInstitute for Natural Hazards and Alpine Timberline, Innsbruck, Austria
Abstract: New technologies like high-speed video recording give new insights into the flowing behavior of snow. At the SLF snow chute at Weissfluhjoch Davos a setup was developed, which allowed us to record high-speed movies of the ground near shear layer of the chute flows with a frame rate of 1000 frames per second. Frictional and collisional processes can be observed in high slow motion in the videos obtained. Downstream velocity profiles were generated by a pattern matching algorithm and compared to velocity profiles obtained from optical sensors mounted next to the high-speed camera. The comparison shows good agreement for most experiments. The temporal and spatial resolution is much higher for the high-speed video data. Because the optical velocity sensors only measure velocities in downstream direction they overestimate the velocities when flow-normal velocity components exist as well. All measured velocity profiles show very high shear rates near the ground. The height of the this highly sheared zone depends on snow properties. Above this highly sheared zone the shear rates decrease significantly tending to zero for certain snow types.
Keywords: avalanche dynamics, high-speed video recording, snow rheology, chute experiments, pattern matching algorithm
Digital Abstract Not Available