Vegetation is an important component of rivers, present naturally alongside the banks. In this research study, three-dimensional computational fluid dynamics (CFD) code ANSYS FLUENT was used to solve the Reynolds Averaged Navier-Stokes equations and to simulate flow features in an asymmetric vegetated compound channel. Three-dimensional flow characteristics and turbulence properties were captured well by the Reynolds stress turbulence model (RSM). A total of five flow cases were considered in this work. Among these, four cases were of circular vegetation patches present on the floodplain edge and one was of non-vegetated asymmetric trapezoidal compound channel. Impact of vegetation patch density, patch center to center (c/c) spacing and flow blockage area has been investigated on various flow features and compared with flow characteristics in a channel without vegetation. Flow features include mean and depth-averaged velocities, secondary flows, Reynolds shear and normal stresses, turbulence intensities and turbulent kinetic energy. The results show that the presence of vegetation patches along the floodplain imparted flow resistance which shifted the zone of higher velocities towards outer wall of main channel and floodplain. Increased velocities in the main channel up to 24.8% was observed for larger flow blockage (aD, where a is the density of the vegetation patch and D is the diameter of patch) and smaller normalized c/c spacing (L/D, where L is the c/c spacing between two patches and D is the diameter of patch) of patches. Large transverse shear stresses existed around the vegetated zone due to the gradient of velocities and vortices in the main channel and floodplain. Floodplain, especially vegetated zone acquires less Reynolds stresses and turbulence making it favorable for deposition of sediments and growth of ecological species.

植被是河流的重要组成部分，自然地与河岸并存。在这项研究中，使用三维计算流体动力学（CFD）代码ANSYS FLUENT来求解雷诺平均Navier-Stokes方程，并模拟非对称植被复合通道中的流动特征。雷诺应力湍流模型（RSM）很好地捕获了三维流动特性和湍流特性。这项工作总共考虑了五个流程案例。其中，有4例是泛滥平原边缘存在圆形植被斑块，而1例是非植被非对称梯形复合通道。植被斑块密度的影响 已针对各种流量特征研究了贴片中心到中心（c / c）的间距和流量阻塞区域，并将其与无植被通道中的流量特征进行了比较。流动特征包括平均速度和深度平均速度，二次流动，雷诺剪切力和法向应力，湍流强度和湍动能。结果表明，沿漫滩的植被斑块的存在赋予了流动阻力，使较高速度的区域向着主河道和漫滩的外壁移动。对于较大的流量阻塞，观察到主通道中的速度提高到24.8％（结果表明，洪泛区沿岸植被斑块的存在赋予了流动阻力，使较高速度的区域向主河道和洪泛区的外壁移动。对于较大的流量阻塞，观察到主通道中的速度增加了高达24.8％（结果表明，沿漫滩的植被斑块的存在赋予了流动阻力，使较高速度的区域向着主河道和漫滩的外壁移动。对于较大的流量阻塞，观察到主通道中的速度提高到24.8％（aD，其中a是植被斑块的密度，D是斑块的直径）和较小的标准化c / c间距（L / D，其中L是两个斑块之间的c / c间距，D是斑块的直径）补丁。由于主河道和洪泛区的速度和涡流梯度，植被区周围存在较大的横向剪切应力。洪泛区，特别是植被带获得较少的雷诺应力和湍流，使其有利于沉积物沉积和生态物种的生长。