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By using the ANSYS FLUENT numerical simulation software, the Navier-Stokes equation as the governing equation, based on the finite volume method, this paper adopts the standard k -- ε turbulence model to establish a numerical analysis model. Under the condition of constant density, numerical simulation study is carried out on the water flow characteristics of three kinds of rigidly submerged vegetation open channels with thick stems. The results show that the experimental results are compared with the numerical simulation calculation results, and the calculated velocity values are in good agreement with the experimental values, which verifies the correctness and feasibility of the numerical simulation method. By analyzing the flow velocity distribution changes in the flow field, the increase in the thickness of the vegetation stems is obtained. By analyzing the vertical distribution of the flow velocity in the flow field, it is concluded that the slope close to vegetation has a smaller range of velocity change, and the water flow is more turbulent. As the distance from vegetation continues to increase, the vertical velocity change range increases significantly. The mixed turbulence effect of vegetation on the point flow field is weakened. [ABSTRACT FROM AUTHOR]

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(Objective) Most open channels are planted with vegetation to avoid erosion of channel beds and slopes while in the meantime facilitating decontamination of organic and inorganic pollutants in the water. However, the vegetation could detrimentally affect water flow. How the depth and growing direction of the vegetation affect water flow across the channel is an issue not well understood. The objective of this paper is to plug this gap. (Method) A physical model was established to simulate water flow in open channel with the vegetation taken into account. Water in the channel was divided into two layers: A vegetation layer and an overlaid free layer. The impact of the growing direction of the vegetation, characterized by their stem inclination angle, was studied experimentally. (Result) 1 When the inclination angle of the stems was the same, the water velocity in the vegetation layer, Vv, tended to level off as the water depth in the channel, h, increased. In the free layer, the average velocity, Vs, the Reynolds number Res, Froude number Frs increased asymptotically as h increased. 2 We found that Vv, Rev and Frv in the vegetation layer were spatially anisotropic varying with the stem inclination angle, while in the free layer Vs, Res and Frs decreased as the stem inclination angle increased. There was a delay in the critical water depth above which the vegetation was submerged. (Conclusion) Water velocity Vs, Res and Frs in the free layer were higher than that in the vegetation layer. Water flow in the vegetation layer was slow and turbulent, while in the free layer the water flow was rapid, in a transition from fast turbulence to slow turbulence. Our results can help open channel design on how to reduce erosion of its bed and slope by growing vegetation without risking flooding. [ABSTRACT FROM AUTHOR]

Copyright of Yellow River is the property of Editorial Board of Yellow River and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)