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A Numerical Simulation of Aeolian Snow Ripples on Dynamic Surface

Xinghui Huo 1 ,2, Guang Li1 ,2, Ning Huang1 ,2
1Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University), The Ministry of Education of China, Lanzhou,Gansu, China, 2Department of Mechanics, School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou,Gansu, China

Grains entrained by the wind impact on the snow bed causes saltation, which is the dominating way of snow transport near the ground. Resulting from the interaction between saltation of snow particles and topography, Aeolian snow beds exhibit regular patterns of ripples. But until now, the mechanism of their emergence remains unknown. In this work, a numerical model with wind-snow transport and dynamic ground surface is established to simulate the generation of snow ripples. The wind field is evaluated from RANS. Saltation particles are simulated by Lagrange particle tracking method (LPT) and the splash function of snow. Immersed boundary method is applied to simulate the dynamic topography. By coupling particle transportation, wind field and dynamic boundary, the amount of snow particles taking part in depositions/erosions, and further the formation and evolution of snow ripples can be obtained directly. The work also shows that by considering the gravity-induced creep particles, snow ripples will finally keep a certain height. And the wavelength of ripples are determined by the average saltation length of grains.