Longitudinal variations of hydraulic characteristics of overland flow with different roughness

作     者：王协康 闫旭峰 周苏芬 黄尔 刘兴年 WANG Xie-kang;YAN Xu-feng;ZHOU Su-fen;HUANG Er;LIU Xing-nian

作者机构：State Key Laboratory of Hydraulics and Mountain River EngineeringSichuan University Yangtze River Scientific Research Institute Department of Civil and Structural EngineeringThe Hong Kong Polytechnic University 

出 版 物：《Journal of Hydrodynamics》 (水动力学研究与进展B辑（英文版）)

年 卷 期：2014年第26卷第1期

页      面：66-74页

核心收录：

学科分类：08[工学] 081502[工学-水力学及河流动力学] 0815[工学-水利工程] 

基　　金：Project supported by the National Natural Science Foundation of China(Grant No.41171016) 

主　　题：overland flow longitudinal hydraulic characteristics flow resistance quadratic interpolation 

摘      要：The evolution of the overland flow velocity along the distance downslope on smooth and granular beds in different cases is investigated by means of the electrolyte tracer via flume experiments. The results demonstrate that a non-uniform flow regime and a uniform flow regime exist in the development process of the overland flow. Owing to the different attributes of beds＇ roughness, the position of those zones with different flow regimes varies correspondingly：（1） the overland flow on granular beds enters into the uniform regime much sooner, additionally, the roll waves tend to appear because of the presence of the proper flow resistance impa-rted by the roughness （coarse sands）, and large slopes （20o and 25o） which makes the flow velocities and depths to undulate spatially. Furthermore, the flow resistance of the overland flows with different roughness elements, that is the non-sands, the fine sands and the coarse sands, is calculated. A quadratic interpolation method of the third order accuracy is employed in the calculation of the longitu-dinal flow resistance. The results show that it is rational to use the bed slope to approximate the hydraulic energy slope over a rela-tive small roughness （the present roughness）, however on the other hand, if the mean flow velocities and depths rather than the local parameters are used to calculate the flow resistance, a considerable error will be induced within the non-uniform regime of the over-land flows, including the acceleration zone and the roll-wave zone.