【摘要】 本文通过在水槽实验中采集的流速过程数据,定量地研究了沙纹阶段明渠水流在不同形式扰动作用下的湍流结构,以及湍流结构对泥沙运动和床面演化的影响。实验发现,扰动附近水流紊动大大增强,扰动促使局部泥沙在断面平均流速低于平床起动流速的情况下起动,并促使床面失稳形成沙纹。另外,不同的扰动形式、位置及尺度对泥沙运动以及床面稳定性的影响各不相同,实验中进行了深入的比较和分析。更多还原

【Abstract】 Disturbances with various patterns were exerted to the open channel flow in a flume to quantitatively investigate the variation of turbulence structure during sand ripple formation and its influence on sand movement and river bed evolution. The variation process of flow velocity is measured by means of ADV with sampling frequency of 50Hz.The result shows that the disturbances enhance the movement of sand,so that the incipient velocity of local sand will lower than that on the flat river bed and lead to instability of river bed and sand ripple consequently.Besides,disturbances with different patterns,positions and scales may have different influences on bed stability.更多还原