A Fragment Model of Spherical Snow Particles Based on Discrete Element Method

Fragmentation of snow particles constitutes a key physical process within drifting snow, exerting a vital influence on the mass and energy balance of the polar ice sheet as well as the redistribution of snow cover. In this study, we put forward a model for the collision and fragmentation of snow particles with a rigid bed surface based on the discrete element method and investigate the intrinsic mechanism of snow particle fragmentation under various impact conditions. The results demonstrate that the fragmentation of snow particles is predominantly governed by the normal component of the impact velocity relative to the bed surface. After the collision, snow particles generally break into one major fragment and several small fragments. Among them, the size of the major fragment decreases power exponentially with the normal impact velocity. The number of effective fragments (i.e., equivalent diameter is greater than 0.1 times the initial diameter.) initially increases and subsequently decreases with the normal impact velocity, peaking at around 8 m/s, and the size of small fragments follows a lognormal distribution. Furthermore, the critical velocity for snow particle fragmentation decreases linearly with the increase of the impact angle. Moreover, a complete fragmentation scheme for snow particle-snow bed collision is given, which can provide an effective fragmentation model for blowing snow and further deepen the understanding of the movement of the two-phase flow of wind and snow.