Numerical Simulation of Drifting Snow Saltation and Suspension
Guanglei Shi, Ning Huang
Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University), The Ministry of Education of China, Lanzhou, Gansu, China
Both saltation and suspension are important parts of drifting snow. Current models of drifting snow concentrate on the research of saltating particles. Some researchers argued that suspension is mainly caused by turbulent flow, and suspension can be described when effects of turbulent flow is taken into consideration in saltation models of drifting snow, but this method can only qualitatively describe suspension of snow particles. Some other researchers use semi-empirical formulae of the saltation concentration at a given height as boundary conditions of suspension. However, these semi-empirical formulae are very depend on experiment results. In this paper we develop a general model of drifting snow, which includes both saltation and suspension. Through analyzing the snow particles ejected from snow surface by saltating particles, a judging criteria of suspension particles from saltating particles is proposed. Then diffusion equation is applied to simulate suspension of snow particles. The results show that the snow transport rates of both saltation and suspension increase with friction velocity. The snow transport rate of saltation is far less than that of suspension. And the time of saltation attaining dynamic balance is also far less than that of suspension.