含淹没植物河流水流紊动强度最大值及其影响因素

根据含淹没植物河流水流紊动强度与流速和流速分布的关系,建立紊动强度经验公式,并数学推导证明了紊动强度垂向分布最大值的存在。根据实验数据,该紊动强度最大值的大小及出现位置受植物和水流条件的影响:植物的存在增加水流阻力,植物排列密度改变紊动强度最大值的大小;植物叶片的摆动形成水流紊动的主要干扰源,植物/水深相对高度控制紊动强度最大值的出现位置;断面平均流速的变化改变水流的稳定性和植物冠层的高度,对紊动强度最大值的大小和出现位置均有一定影响。

Turbulence intensity maximum and its influence factors in submerged river flow with plant

An empirical formula for the turbulence intensity in subemerged river flows with plant is deduced,considering turbulence intensity as a function of velocity and its gradient.The existence of the turbulence intensity maximum is validated mathematically according to this formula.According to the laboratory experiments,the magnitude and location of the turbulence intensity maximum is influenced by both the submerged canopy and the river flow.The foliage-spacing influences the magnitude of the maximum turbulence intensity by increasing the resistance of river flow.The swing of the frond foliage contributes to the initial disturber of turbulence,therefore the location of this maximum is controlled by the canopy/water-depth ratio.The cross-sectional averaged velocity influences the stability of water flow and the height of bend canopy,therefore modifying the magnitude and location of this maximum.