【摘要】 依据风沙运动实验相似理论,以新疆和田河流域实测的柽柳沙堆形态数据为基础,按40∶1的比例缩小制成半球形和圆锥形模型,并在模型顶部模拟人工“植物灌丛”,选用起沙风速区间在6~14m.s-1的5组不同的风速分别对半球形灌丛沙堆模型和圆锥形灌丛沙堆模型在风洞中作纯气流流场模拟实验,以探讨植物在灌丛沙堆绕流结构形成中的作用。模拟实验表明,无论沙堆基本形态如何变化,沙堆顶部的植物都增加了沙堆表面的粗糙度,对翻越沙堆的绕流气流阻滞消能,消除了裸露沙堆顶部常见的强风侵蚀区域,并加强了背风坡涡流影响范围,这种流场结构变化必将影响沙堆前后风沙流的结构特征。因此,植物的存在将更有利于截留沙尘、促进沙堆增长,植物在沙堆发育过程中起着十分重要的作用。更多还原

【Abstract】 In this paper,two models of nabkhas were made in 40:1 proportion in wind tunnel,according to similarity theory in wind-sand movement experiments,and on the base of nabkhas data surveyed in the Hetian river basin in Xinjiang.The airflow patterns over the semispherical and the conical models were simulated under pure wind with speed of 6,8,10,12,14 m\5s^-1 separately.Experimental results showed that plants at the top of sand mounds can enhance the roughness of sand surface,reduce airflow energy and retard airflow to get over the sand mounds,and can eliminate the eroded region by strong wind that appeared commonly on bare sand mounds,and reinforce the influencing range of vortex at leeward side.Consequently,the structural characters of wind-sand flow in front of and behind the sand mounds must change.Therefore,the vegetation on sand mounds is benefit to hold flowing dust and sand,and to promote dunes to be accumulated.Vegetation has played a very important role in the course of nabkhas development.更多还原