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通过物理模型试验、理论分析和数值模拟的方法,研究了有水浮莲覆盖水流的纵向流速垂线分布规律.在水浮莲全覆盖条件下,初步对比分析了3种不同工况下水流纵向时均流速的变化趋势和垂线分布特点.通过“双层边壁”假设,以最大流速线(点)为界将流动沿水深方向分成两层等效明渠流流动层:植被下层和床面上层,并假定上下两层互不影响,即分别只受植被底部和床面粗糙程度影响;利用混合长度模型简化时均动量方程,推导出有水浮莲覆盖水流在恒定均匀流下的纵向时均流速对数分布公式;根据实测数据对公式进行了验证分析.水浮莲对水流影响的数值模拟主要利用计算流体力学软件FLUENT,结合可实现双方程紊流模型,对有水浮莲覆盖的水槽二维两相流场作了数值模拟,并采用多孔介质域模拟水浮莲覆盖区域,将数值计算得到的流速分布与试验实测结果进行了比对,两者吻合较好.
Through the physical model test, theoretical analysis and numerical simulation, the vertical distribution of the vertical velocity of water covered with water hyacinth was studied.Under the condition of full coverage of water hyacinth, the vertical distribution of water flow under three different operating conditions The trend of the average velocity and the vertical distribution of the flow velocity are discussed.It is divided into two layers of equivalent open channel flow along the depth of water by the maximum velocity line (point) as the boundary of the “double wall” The upper layer and the lower layer are assumed to be independent of each other, that is, they are affected only by the bottom of the vegetation and the roughness of the bed surface respectively. Using the hybrid length model, the time-averaged momentum equation is simplified to derive the vertical The logarithmic distribution of flow velocity was calculated and the formula was validated based on the measured data.Numerical simulation of water flow influenced by water hyacinth mainly by using the FLUENT software combined with the dual equation turbulence model, Of the two-dimensional two-phase flow field of the tank for numerical simulation, and the use of porous media to simulate the area covered by water hyacinth, the calculated flow velocity distribution and the experimental results were compared Are in good agreement.