Numerical Simulation of the Influence of Riparian Vegetation on Hydrodynamic Characteristics of a Compound River

被引：0
|
作者：
Hao Y. [1 ]
Jia D. [1 ,2 ]
Zhang X. [1 ]
Chen C. [1 ]
Wu L. [1 ]
Yang J. [1 ]
机构：
[1] Key Lab. of Port, Waterway and Sedimentation Eng. of Ministry of Transport, Nanjing Hydraulic Research Inst., Nanjing
[2] Yangtze Inst. for Conservation and Development, Nanjing
来源：
Gongcheng Kexue Yu Jishu/Advanced Engineering Sciences | 2023年 / 55卷 / 03期
关键词：
compound channel; flow characteristics; numerical simulation; Reynolds stress model; riparian vegetation;
D O I：
10.15961/j.jsuese.202101266
中图分类号：
学科分类号：
摘要：
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 momentum exchange between the floodplain and the main channel without vegetation gradually decreases. However, when non-submerged rigid vegetation is planted on slope, the attenuation degree of momentum exchange will be weakened.; 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 momentum exchange between the floodplain and the main channel without vegetation gradually decreases. However, when non-submerged rigid vegetation is planted on slope, the attenuation degree of momentum exchange will be weakened. © 2023 Editorial Department of Journal of Sichuan University. All rights reserved.
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页码：149 / 157
页数：8
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