摘要
广泛分布于天然河道岸坡的植被能够改变河道水流特性,进而影响坡脚淘刷、河岸稳定及河道形态演变趋势。为精细揭示岸坡植被对复式河道水动力特性的影响,将植被作为固壁边界,利用雷诺应力模型封闭紊流控制方程构建了复式河道3维水动力数学模型,并对复式河道水流特性进行了模型验证,模拟结果与实测结果吻合较好。将该模型应用于岸坡有植被的复式河道开展水流特性研究,对比种植非淹没刚性植被、种植淹没刚性植被、淹没与非淹没刚性植被交替种植和无植被情况下流速、流量、河床剪应力、雷诺应力及紊动能分布的差异。结果表明:岸坡植被加剧了滩槽间横向动量交换,引起二次流涡旋数量、强度和范围的增加,同时使得横断面流速、流量分配、河床剪应力、雷诺应力及紊动能在滩槽交界区显著减小,紊动交换在临近植被的周边区域明显增加。其中,岸坡种植非淹没刚性植被时对水流特性影响最为显著,相比无植被情况,种植非淹没刚性植被后,二次流结果显示增加了一对涡旋;岸坡植被区流速、流量分配、河床剪应力、雷诺应力及紊动能大幅减小,甚至趋近于0;而临近植被的周围区域紊动交换剧烈,无量纲化的紊动能值可达到20。此外,随着河岸坡比减小,无植被河道滩槽间动量交换逐渐衰减,而坡面种植非淹没刚性植被后,则会减弱动量交换的衰减程度。
The riparian vegetation can change the characteristics of the river flow,thereby affecting the bank erosion,bank stability and the river evolution trends.In order to clarify the influence of riparian vegetation on the hydrodynamic characteristics,the method treating the vegetation as a solid wall boundary was proposed.Using the Reynolds stress model to close the turbulence equation,a three-dimensional hydrodynamic numerical model for the compound channel flows was constructed.The flow characteristics model of the compound channel under the condition of no vegetation was verified first.The model was then applied to the study of the water flow characteristics of a compound river with vegetation on the bank slope.The differences in the distribution of velocity,flow,river bed shear stress,Reynolds stress,and turbulence kinetic energy under emerged rigid vegetation,submerged rigid vegetation,alternating emerged and submerged rigid vegetation,and no vegetation were compared.The results show that vegetation intensifies the momentum exchange between the floodplain and the main channel,causing the increase in the number,the intensity and the range of secondary current vortexes.At the same time,the cross-sectional flow velocity,flow,river bed shear stress,Reynolds stress and turbulence kinetic energy are significantly reduced in the beach-trough junction area,and the turbulence exchange was significantly increased in the area around the vegetation.The effect is most significant when emerging rigid vegetation is planted on the bank slope.Compared with the case of no vegetation,the number of secondary flow vortices increases by one pair,and the velocity,flow distribution,river bed shear stress,Reynolds stress and turbulence kinetic energy of the bank slope vegetation area are greatly reduced and even close to zero.The turbulence exchange in the surrounding area near the vegetation is intense,and the dimensionless turbulence kinetic energy value can be increased to 20.In addition,as the riparian slope ratio decreases,the mome
作者
郝由之
假冬冬
张幸农
陈长英
吴磊
杨俊
HAO Youzhi;JIA Dongdong;ZHANG Xingnong;CHEN Changying;WU Lei;YANG Jun(Key Lab.of Port,Waterway and Sedimentation Eng.of Ministry of Transport,Nanjing Hydraulic Research Inst.,Nanjing 210029,China;Yangtze Inst.for Conservation and Development,Nanjing 210098,China)
出处
《工程科学与技术》
EI
CSCD
北大核心
2023年第3期149-157,共9页
Advanced Engineering Sciences
基金
国家自然科学基金项目(U2040215,52079080)。
关键词
岸坡植被
水流特性
复式河道
雷诺应力模型
数值模拟
riparian vegetation
flow characteristics
compound channel
Reynolds stress model
numerical simulation
