Flow behaviour of snow in a rotating drum

München

2017

Sonderdruck

202736

Snow, rapidly moving in an avalanche, transforms along the avalanche path, and consequently changes the flow
behaviour over time. Recent studies showed that this expected change is particularly pronounced at temperatures
above -2C. Since investigations in the field are connected to considerable challenges, we aim to investigate the
flow behaviour and the dynamic transformation of snow continuously at (relatively) controlled boundary conditions
at a scale as large as possible. We therefore create a continuous movement of snow in a vertically rotating drum
with a diameter 2.5 m and a rectangular cross section of 0.45 m. Experiments in our outdoor facility were carried
out at temperatures below freezing and at tangential velocities between 0.1 and 1 m/s. To avoid basal slip semicircular roughness elements with a height of 1 cm were installed. We present results of measurements of snow
temperature, the liquid water content of snow, as well as flow geometry, basal normal stress distribution, and bulk
shear stress over time. Furthermore we link the thermal energy increase to the equivalent vertical travel distance
of the flow. The outcomes of this study shall increase our understanding of the material snow and consequently
contribute to an improved model building for avalanche simulations.