非定常阵风场对沙粒跃移运动的影响浅析

INFLUENCE OF THE UNSTEADY TURBULENCE IN FIELD GUST ON SAND SALTATION

  • 摘要: 野外阵风具有大尺度结构的非定常特征和小尺度结构的高频脉动特性,是造成风沙流输沙量波动和沙粒间歇性跃移的主要原因. 阵风的非定常性和脉动越显著,采用平均风速及沙粒粒径均一化分析风沙问题的误差越大,是野外观测、风洞实验及数值模拟的结果彼此偏差极大的主要因素. 野外阵风条件下的风沙跃移研究目前仍缺乏能够用于规范数学模型的有关阵风场和输沙率特征的可靠实时测量,有赖于风沙流整场高频测量技术和风洞模拟技术的发展.

     

    Abstract: In the study of the aeolian sand saltation, the interactions between the wind and the sand particles are the key. Both the macro-sized unsteady feature and the micro-sized high frequent turbulence prevalent simultaneously in the field gust would lead to the fluctuant sand-transport rate and the intermittent saltation process in the wind-sand flow. While the time-averaged wind velocity is used to analyze the natural wind-sand flow, the high unsteady feature and the turbulent intensity in the flow would cause huge errors. It may be the reason why the results derived from the field observation, the wind-tunnel experiment and the numerical simulation have great deviations. The sand saltation within the wild gust field is an important research issue. Unfortunately, there are few reliable instantaneous measurements on the whole flow field to validate the related mathematical model. The development of the whole field measurement with high frequency in the wind-sand flow and the simulation technique of the field gust in the wind tunnel would solve this problem.

     

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