小角度斜向入流条件下复式断面明渠流速重分布线性理论

许栋; 黄雄合; 及春宁; 白玉川

doi:10.21656/1000-0887.380183

小角度斜向入流条件下复式断面明渠流速重分布线性理论

doi: 10.21656/1000-0887.380183

水利工程仿真与安全国家重点实验室(天津大学), 天津 300072

基金项目: 国家自然科学基金创新研究群体项目(51621092)；国家自然科学基金(51579175;51009105)；天津市科技支撑计划(16ZXCXSF00020)；天津市应用基础与前沿技术研究计划(12JCQNJC05600)

详细信息

作者简介:
许栋(1980—)，男，副教授，博士（通讯作者. E-mail: xudong@tju.edu.cn）.

中图分类号: TV133
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出版历程
- 收稿日期: 2017-06-28
- 修回日期: 2018-05-23
- 刊出日期: 2018-07-15

Linear Theory of Velocity Redistribution for Flow in Compound Open Channels Under Inflow With Small Oblique Angles

State Key Laboratory of Hydraulic Engineering Simulation and Safety(Tianjin University), Tianjin 300072, P.R.China

Funds: The National Natural Science Foundation of China(51621092; 51579175;51009105)

摘要

摘要: 自然界中复式河道的来流方向常受径流量、滩槽形态影响，往往与主槽存在小幅度夹角，使得目前基于顺直河道假定的漫滩水流大量的理论成果难以适用.为研究斜向入流影响，采用平面二维浅水方程描述沿程均匀的复式断面明渠水流运动，选取斜向角度作为小参数，运用摄动法推导了小角度（θ<20°）斜向入流条件下复式河道流速分布的线性解析解，并利用数值模拟结果进行验证，流速分布吻合较好.理论分析结果表明，斜向来流时由于出现垂直于河道方向流速分量，使得顺河道方向流速沿河宽分布偏离正向来流情况下的对称形态而重新分布，入流侧流速减小而对岸流速增大；在斜向角度θ=13°且滩槽水深比为3∶8的情况下，偏离幅度可达21.8%，该幅度随滩槽水深比的减小而增大.该文针对斜向来流对流速分布的修正将为进一步研究复式河道泥沙运动和河流演变提供更为准确的水动力条件.
- 复式河道 /
- 小角度斜入流 /
- 摄动法 /
- 线性理论
Abstract: The directions of flow in natural compound river channels are frequently influenced by the discharge and floodplainmain channel configuration, which may lead to a small intersection angle between the flow and the channel. Hence, lots of existent theories for floodplain flows under the assumption of uniform straight channels may be inapplicable. To investigate the influence of oblique inflow, shallow water equations were used to describe flow motion in compound open channels. The perturbation method was used with a small parameter of the oblique angle to derive the analytical solution for flow in compound open channels under inflow with small oblique angles. The solutions were verified with numerical simulation results and the flow velocity distributions agreed well. Theoretical results show that the obliquity of inlet flow lead to asymmetrical velocity distribution across the cross section of a compound channel, which is featured by an increase of velocity in the upstream side and a decrease in the downstream side of the main channel. Under an oblique angle of 13° and a floodplainmain channel water depth ratio of 3∶8, the flow velocity deviation may reach 21.8% of the value in the straight flow case. Such a deviation increases with the decreasing of the floodplainmain channel water depth ratio. The proposed modification to flow velocity distribution may improve the accuracy of hydrodynamic conditions for further research on sediment transport and evolutions of compound channel rivers.
- compound channel /
- small oblique angle inflow /
- perturbation method /
- linear theory

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