自然河道断面水动力模拟的黎曼求解器改进  

Improvement of riemann solver for hydrodynamic simulation of natural river channel sections

作　　者：位昊昆 高希超 冯杰[1,2] 杨志勇 WEI Haokun;GAO Xichao;FENG Jie;YANG Zhiyong(State Key Laboratory of Watershed Water Cycle Simulation and Regulation,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Key Laboratory of River Basin Digital Twinning of Ministry of Water Resources,Beijing 100038,China)

机构地区：[1]中国水利水电科学研究院流域水循环模拟与调控国家重点实验室,北京100038 [2]水利部数字孪生数字流域重点实验室,北京100038

出　　处：《水利水电技术（中英文）》2024年第9期26-37,共12页Water Resources and Hydropower Engineering

基　　金：国家重点研发计划(2022YFC3002702);国家自然科学基金资助项目(52209044);流域水循环模拟与调控国家重点实验室团队项目(SKL2022TS11)。

摘　　要：【目的】自然河道具有断面复杂、流态多变等特点,影响了水动力模拟的收敛性、稳定性,在已有研究基础上,改进复杂断面的黎曼求解器以解决低水位时断面不连续造成的数值不稳定问题,对提升自然河道一维水动力模拟的适用性具有重要意义。【方法】对低水位时存在“锥形凹陷”形态特征的复杂自然河道断面,传统不规则断面HLL黎曼求解器模拟时,会在河道干湿界面处出现通量演进受阻问题,针对上述问题,在河道干湿界面处直接采用界面流量值代替传统不规则断面HLL黎曼求解器计算的通量,改进传统黎曼求解器,使其能够适用于存在“锥形凹陷”形态特征的复杂自然断面河道干湿界面模拟,基于改进后的黎曼求解器构建不规则河道断面一维水动力模型,并采用五个通用算例对该方法在不同条件下的适用性进行了验证。【结果】结果显示:在一维溃坝算例中,对存在“锥形凹陷”特征的复杂河道断面,采用传统不规则断面HLL黎曼求解器模拟时,在河道干湿界面处出现了数值失稳和通量演进受阻问题,应用改进后的HLL求解器可以有效解决上述问题,数值解与理论解的相关系数高于0.99,结果准确可靠;在三角形挡水建筑物溃坝试验中,模型对4个测站的洪水到达时间和洪水过程的模拟结果与实测数据吻合,相关系数都在0.95以上;在一维过驼峰恒定流算例和急缓流交替模拟的陡坡河道水面线计算中,模型与传统模型表现相当,都能正确地预测不同河道断面形状下水跃位置和水跃前水深的变化;在长江口澄通河段潮位模拟算例中,模型预测的4个观测站点的潮位模拟数据与实测数据相关系数都在0.99以上,均方根误差都在0.08以内。【结论】结果表明:改进后的黎曼求解器可有效解决自然河道存在“锥形凹陷”形态特征导致水动力模型在干湿交界处通量演进受阻问题,构建�[Objective]Natural rivers have the characteristics of complex cross-sections and variable flow patterns,which affect the convergence and stability of hydrodynamic simulations.Based on existing research,improving the Riemann solver for complex cross-sections to solve the numerical instability problem caused by discontinuous cross-sections at low water levels is of great significance for enhancing the applicability of one-dimensional hydrodynamic simulations of natural rivers.[Methods]For complex natural river sections with“conical depression”morphology characteristics at low water levels,the traditional irregular section HLL Riemann solver may encounter flux evolution obstruction at the dry wet interface of the river.To address this issue,the interface flow value is directly used at the dry wet interface of the river to replace the flux calculated by the traditional irregular section HLL Riemann solver.The traditional Riemann solver is improved to make it suitable for simulating the dry wet interface of complex natural river sections with“conical depression”morphology characteristics.Based on the improved Riemann solver,a one-dimensional hydrodynamic model of the irregular river section is constructed,and the applicability of this method under different conditions is verified using five universal examples.[Results]The result showed that in a one-dimensional dam failure case,for complex river sections with“conical depression”characteristics,numerical instability and obstructed flux evolution occurred at the dry wet interface of the river when simulated using the traditional irregular section HLL Riemann solver.The application of the improved HLL solver can effectively solve the above problems.The correlation coefficient between the numerical solution and the theoretical solution is higher than 0.99,and the result are accurate and reliable;In the dam failure test of triangular water retaining structures,the simulation result of the flood arrival time and flood process at four measuring stations by the mo

关 键 词：一维水动力模型 有限体积法 不规则河道断面 干湿界面 径流 数值模拟 水力特性 洪水预报 

分 类 号：TV131.2[水利工程—水力学及河流动力学]