POINTWISE AND UPWIND DISCRETIZATIONS OF SOURCE TERMS IN OPEN-CHANNEL FLOOD ROUTING

作     者：MENG Jian CAO Zhi-xian CARLING Paul A. 

作者机构：College of Information Management Wuhan University Wuhan 430072 China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan430072 China School of Geography University of Southampton Highfield SO17 1B J UK 

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

年 卷 期：2006年第18卷第4期

页      面：379-386页

核心收录：

学科分类：080103[工学-流体力学] 08[工学] 080104[工学-工程力学] 081502[工学-水力学及河流动力学] 0815[工学-水利工程] 0801[工学-力学（可授工学、理学学位）] 

基　　金：Project supported by the Open Research Fund of the State Key Laboratory of Water Resources and Hydropower Engineering Science  and the National Natural Science Foundation of China (Grant No: 50459001) 

主　　题：St-Venant equations upwind scheme,pointwise discretization source term pool-riffle sequence flow reversal flood routing 

摘      要：Upwind algorithms are becoming progressively popular for river flood routing due to their capability of resolving trans-critical flow regimes. For consistency, these algorithms suggest natural upwind discretization of the source term, which may be essential for natural channels with irregular geometry. Yet applications of these upwind algorithms to natural river flows are rare, and in such applications the traditional and simpler pointwise, rather than upwind discretization of the source term is used. Within the framework of a first-order upwind algorithm, this paper presents a comparison of upwind and pointwise discretizations of the source term. Numerical simulations were carried out for a selected irregular channel comprising a pool-riffle sequence Jn the River Lune, England with observed data. It is Shown that the impact of pointwise discretization, compared to the upwind, is appreciable mainly in flow zones with the Froude number closer to or larger than unity. The discrepancy due to pointwise and upwind discretizations of the source term is negligible in flow depth and hence in water surface elevation, but well manifested in mean velocity and derived flow quantities. Also the occurrence of flow reversal and equalisation over the pool-riffle sequence in response to increasing discharges is demonstrated.