MODELLING OF WIND FLOW PATTERN AFFECTING SNOWDRIFT

Abstract

The wind is a significant metrological parameter which is used in wind energy harvesting and assessment of aeolian phenomena. It transports snow from one place to another place known as snow drifting and the deposition pattern of the natural precipitated snow is changed. The snow drifting causes many problems like invisibility, snow cornice formation and blockages of highways. Due to the failure of snow cornices, the snowpack on the formation zone of an avalanche is destabilized and trigger an avalanche. The wind-driven snow on the surface is comparatively more compact and it stays for a longer period in the region. In the mountainous region, wind transport snow from windward to leeward side and excess snow deposition on the leeward formation zone trigger avalanche. Fracture initiation and propagation in snowpack are generated due to the self-weight of the snow (Mahajan et al., 2010). Seeing the contributions of wind-driven avalanche hazard, the researchers have tried to simulate and model the snowdrift using numerical methods and wind tunnel experiments. The study of wind profile and its effect on the snowdrift is beneficial for avalanche forecasting, snowdrift control and planning of protection of highways in the mountainous regions. The logarithmic wind speed profile and various modifications to it are further used in stable stratification at inappropriately high altitudes (A. Clifton et al., 2006; Gryning et al., 2007; Kent et al., 2018). With the similarity theory based on the Monin-Obukhov concept, the profiles of wind speed and turbulence can be calculated as per Eq. 1.1 (Tennekes, 1973). (1.1) Where u(z) is the wind velocity at height z, roughness length z0, Friction velocity u*, Monin-Obukhov length L*, stability correction  and Von Karman constant =0.4. The Monin-Obukhov theory applies restricted to the surface layer (roughly 10% of the height of the atmospheric boundary layer) (Cenedese et al., 1997). Computational fluid dynamics technique is used to simulate the wind flow around the hill and the snowdrift control structures for mitigation of avalanche hazard in the mountainous region. The modelling of wind flow around snowdrift control structures (snow fence and Jet roof) and investigation of a new simulant material, foam beads (expanded Polystyrene) for snowdrift modelling have been carried out under the research work.