| 沙漠与沙漠化 |
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| Numerical Simulation of the Near-surface Particle Concentration at the Early Stage of Blown Sand Emission |
| LI Yin-tang, SHE Yuan-yuan, MENG Hai-yan |
| School of Energy and Power Engineering, Xian Jiaotong University, Xian 710049, China |
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Abstract A numerical simulation method is used to investigate the wind-blown sand near the surface at the early entrainment stage. Taking into account the shear and bulk viscosity, the inter- phase momentum exchange, the lift force, etc., a two-dimension mathematic model is developed for gas-solid two-phase flow. Numerical calculations are carried out using Fluent software. The model and its algorithm are verified by simulating blown sand transport in a wind tunnel. The region simulated is 1 000 m long and 500 m high. An exponential function is taken as the vertical profile of wind velocity. An R-R function is adopted to describe the distribution of dust volume fraction, and their diameters are 5~150 μm. The velocities of wind and grains, the spatial distribution of grains volume concentration are obtained from the calculation results. It is shown that the suspension layer can be divided into three sections: developing, declining and steadying. The length of the developing section, the height of suspension layer and the shape of sand concentration profile change with particle size and characteristic velocity of wind.There is a clear band of uniformly saturated sand concentration in the suspension layer immediately above the surface. Its dust concentration and height depend upon particle size and wind velocity. Above the saturated layer, the sand concentration decreases exponentially with an increase in height.
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Received: 23 July 2009
Published: 20 May 2010
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2010, Vol. 30 
