横向沙丘表面气流湍流特征野外观测

沙丘形态动力学特征是风沙地貌的重要研究内容之一,受观测技术等的限制,现有的关于沙丘形态动力学特征的研究成果还不能满足沙丘形成与演化过程研究的需要。利用三维超声风速仪对腾格里沙漠的横向沙丘表面气流特征进行野外观测,结果表明,沙丘脊线和迎风坡中部的气流均为未偏向流,而沙丘背风坡不同高度的气流包括反向流,偏向流和未偏向流。湍流强度、雷诺应力和气流丰富度随气流方向变化而变化,其在沙丘脊线和中部的变化趋势比较简单且有大致相似的规律,而其在沙丘背风坡不同高度比较复杂。

Field Observation on the Flow Turbulence Characteristics Over Transverse Dune

Dune morphology dynamic is one of the main issues in aeolian geomorphology research. Because of the restriction of measurement technology, the research result on the aeolian geomorphology dynamic is unable to meet the need for dune formation and development at present. Sonic anemometer could measure the high frequency three direction wind velocity simultaneously, and could provide detailed flow information over dune surface. The results indicated that the flow structure at dune ridges and middle part is deflected; however, the flow structure at dune toe is reversal, deflected and undeflected. The flow direction at the ridge is asymmetric for the formation of reversal and deflected flow at the toe. Turbulence intensity, Reynolds stress and flow exuberance changed with flow direction, and has the similar rule at the dune ridge and middle part over dune surface, but it’s complicated at dune toe.