Flow and deposition measurement of foam beads in a closed re-circulating wind tunnel for snowdrift modelling

Abstract

A facility was created for flow and deposition measurement of foam beads (Expanded Polystyrene) in a closed re-circulating wind tunnel to model the snowdrift experimentally. The geometrical and flow similarities between the model (foam beads) and prototype (snow) particles were established for the wind tunnel experiments. The wind tunnel was instrumented with the electronic regulator, anemometer and newly developed flux measuring sensors along with a data logger to carry out the experiments for different simulated terrain conditions. An array of optical sensors for measurement of foam beads flux was calibrated with the known quantity of the material and used to find the flux variation with wind speed inside the tunnel. All three modes of drifting transportation namely creeping, saltation and suspension could be observed through the transparent acrylic wall for data collection. The threshold velocity of foam bead movement was 4.05 m/s in the horizontal section and same was 2.7 m/s in the inclined section at an angle of 30° downward (a critical angle of avalanche starting zone). The process of snow deposition by the snow fence was simulated with the foam beads deposition around the scaled model (1:50) of a snow fence in the wind tunnel. The experiments helped to find a flow measuring technique for light drifting material like foam beads and the modelling of drifting snow.