Simulation of the flow of disconnected sand particles of the surface

Malinovskaya E.A.

Institute of Atmospheric Physics A.M.Obukhova RAS, 119017, Moscow, Pyzhevsky Pereulok, 3, p. 1

The interaction of the air flow with the surface consisting of sandy loose particles occurs in a laminar sublayer. When the critical or threshold wind speed is exceeded as a result of streaming due to resistance and the resulting pressure difference, the particle is pushed out of the layer [1-5]. In nature, the sandy surface differs significantly [2] from the artificial one described in [6]. Particles can be movable inside the layer, in particular, to make oscillatory motions [2], which leads to the change of local characteristics and the formation on the microscales of secondary currents - such as jets and vortices with vertical and horizontal axes [2], [7]. Sand particles correspond to sizes from 20 to 400 microns. It is not possible to put a full-scale experiment with modern methods [7], in which it was possible to observe particle oscillations, and even more so the influence of this oscillation on the characteristics of the air flow. In the problem of the flow of particles of a surface, an air flow tangent to the surface is considered. In this regard, it is possible to note the similarity with the phenomena observed in the flow around the lattice of balls in the direction of the air flow normal to the surface [8]. Analytical estimates are made based on the assumption of the effect of the flows in the channels of the particle layer on the pressing force, based on the theory of jets, for the octahedral packing of particles. In a numerical experiment in solving the problem of laminar flow around a set of spherical balls 100 µm in size, interconnected in the most characteristic scheme, the velocities and characteristics of the pressure at the surface were estimated, which made it possible to determine the conditions for self-stabilization of the layer. This work was financially supported by the Basic Research Program of the Presidium of the Russian Academy of Sciences No. 28 "Cosmos: studies of fundamental processes and their interrelations", the direction "Solar and other planetary systems".

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