Item: Snow avalanche experiments at ski jump
Title: Snow avalanche experiments at ski jump
Proceedings: Proceedings of the 1996 International Snow Science Workshop, Banff, Canada
Authors: K. Nishimura, Y. Nohguchi, Y. It01, K. Kosugi and K. Izumi, 1Institute of Low Temperature Science, Hokkaido University, 2Nagaoka Institute of Snow and Ice Studies, National Research Institute for Earth Science and Disaster Prevention
Abstract: In 1995, we have started the experiments at a ski jump to investigate the avalanche dynamics and internal structures in detail. In winter, natural snow 300 kg in weight at maximum was released and flow velocities, impact pressures, induced wind velocities, and dynamic friction coefficients were measured. The observation setup is almost the same as the one installed in Kurobe Canyon where a systematic investigation of natural snow avalanche is under way since 1989. Instead of snow itself, in summer, we have used 300,000 ping-pong balls. They were stored in a container set on the top of the inclined plane and were released simultaneously. Movements of the individual balls and flow behaviors were recorded with several video cameras. Since the air drag gave a large effect on the ping-pong movement, the flow arrived at a steady state within a relatively short distance. The front velocities strongly depended on the number of released balls. In addition, the flow formed a distinct head and tail structure, which had been often observed not only the snow avalanche but also other large scale geophysical flows in nature.
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Keywords: avalanche experiment, ski jump, ping-pong balls
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