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中文核心期刊

植被作用下的复式河槽流速分布特性

Velocity distribution in compound channels with vegetated floodplains

  • 摘要: 通过水槽试验,探讨了不同滩地植物 (乔木、灌木和野草)对复式河槽流速分布的影响. 详细地介绍试验过程及三维流速仪ADV的测量原理. 试验时,选塑料吸管、鸭毛和塑料大草分别模拟乔木、灌木和野草. 同时,考虑了流量、床面底坡对流速分布的影响. 试验结果表明,滩地未种树的复式河槽在大的相对水深时,流速满足对数分布;滩地种树后,主槽流速增大,流速分布复杂,滩地流速减小,呈S 形分布,不同植物的S 形分布是不同的. 这种S型分布将水流划分为3个区的复杂行为,每区的范围与水深,垂线位置和植物类型有关.床面坡度对流速分布的影响非常明显

     

    Abstract: The authors experimentally studied the velocitydistribution of flows in different types of vegetations such as arbors,shrubs and grass. The experimental procedures and the principle of ADV formeasuring the local velocities are described in detail. For vegetations onthe floodplain, the authors chose plastic grass, duck feathers and plasticstraws as model grass, model shrubs and model arbors, respectively. ADV wasused to measure the local flow velocities for different typesof vegetation on the floodplain, discharges and flume slopes. All measuredstreamwise velocities follow a logarithmic distribution fornon-vegetated floodplain, and obey S-shaped distribution for vegetatedfloodplain. The S-shaped distribution divides the flow into three regions.The range of every region is related to the flow depth, lateral location andvegetation type. For different types of vegetation, the S-shapeddistribution is different. In the meantime, it is found that the velocity inthe main channel increases and that on the floodplain decreases after thefloodplain is vegetated. The increasing or decreasing degree is related tovegetation type. Furthermore, the influences of bed slope on local velocitydistribution for different types of vegetation are distinct.

     

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