三角形河床形态对潜流交换作用的影响
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摘要
为揭示交错三角形河床影响下的潜流交换机理,利用Fluent和COMSOL软件构建了三角形河床地形影响下的地表水-地下水流动的数学模型,并采用试验数据对模型模拟的地表水流速进行了验证,分析了水沙交界面的流速与压力分布和潜流交换区与缓流区的流速分布等。结果表明,河床几何形态促使水沙交界面形成了高低压交错分布的情况,强烈影响着水沙交界面和潜流带的流速分布及大小。波峰上游侧为下降流区域,波峰下游侧为上升流区域。潜流交换区的横向流速与纵向流速分量分别形成了一条"缓流带",其相交区域为潜流交换区的缓流区,缓流区的位置随着三角形河床波峰的位置而变化。研究成果可为三角形河床地带的工程建设提供参考。
In order to reveal the hyporheic exchange mechanism affacted by staggered triangular riverbed,the numerical model developed by Fluent and COMSOL was established to illustrate the flow of groundwater-surface water under the impact of triangular riverbed topography.The surface water velocity simulated by the model was verified by the experimental data.The flow velocity and pressure distribution at the interface of water and sediment and the velocity distribution of the underflow exchange zone and the slow flow zone were analyzed.The results show that the geometrical morphology of riverbed leads to the staggered distribution of high-low pressure,which strongly affects the velocity distribution at the sediment-water interface and hyporheic zone.The upper side of the crest is the downwelling area,and the lower side is the upwelling area.The transverse velocity and the vertical velocity cloud maps of the hyporheic zone form a " stagnation belt",and the intersection region is the stagnation zone of the hyporheic zone.The position of the stagnation zone changes with the position of the triangular riverbed crest.The research results can provide reference for engineering construction of the triangle riverbed area.
In order to reveal the hyporheic exchange mechanism affacted by staggered triangular riverbed,the numerical model developed by Fluent and COMSOL was established to illustrate the flow of groundwater-surface water under the impact of triangular riverbed topography.The surface water velocity simulated by the model was verified by the experimental data.The flow velocity and pressure distribution at the interface of water and sediment and the velocity distribution of the underflow exchange zone and the slow flow zone were analyzed.The results show that the geometrical morphology of riverbed leads to the staggered distribution of high-low pressure,which strongly affects the velocity distribution at the sediment-water interface and hyporheic zone.The upper side of the crest is the downwelling area,and the lower side is the upwelling area.The transverse velocity and the vertical velocity cloud maps of the hyporheic zone form a " stagnation belt",and the intersection region is the stagnation zone of the hyporheic zone.The position of the stagnation zone changes with the position of the triangular riverbed crest.The research results can provide reference for engineering construction of the triangle riverbed area.
引文
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[2]金光球,李凌.河流中潜流交换研究进展[J].水科学进展,2008,19(2):285-293.
[3] Ibrahim A,Steffler P,SheY.Comparison of a Vertically-averaged and a Vertically-resolved Model for Hyporheic Flow Beneath a Pool-riffle Bedform[J].Journal of Hydrology,2018,557:688-698.
[4] Boulton A J,Hancock P J.Rivers as Groundwaterdependent Ecosystems:a Review of Degrees of Dependency,Riverine Processes and Management Implications[J].Australian Journal of Botany,2006,54(2):133.
[5] LEE D H,Kim Y J,Lee S.Numerical Modeling of Bed Form Induced Hyporheic Exchange[J].Paddy&Water Environment,2014,12(S1):89-97.
[6] Endreny T A,Lautz L K,Siegel D I.Hyporheic Flow Path Response to Hydraulic Jumps at River Steps:Flume and Hydrodynamic Models[J].Water Resources Research,2011,47(2):1 198-1 204.
[7] Xiaoru Su,Longcang Shu,Chengpeng Lu.Impact of a Low-permeabilitylens on Dune-induced Hyporheic Exchange[J].Hydrological Sciences Journal,2018,63(5):818-835.
[8] Cardenas M B,Wilson J L.Hydrodynamics of Coupled Flow Above and Below a Sediment-water Interface with Triangular Bedforms[J].Advances in Water Resources,2007,30(3):301-313.
[9] Janssen F,Cardenas M B,Sawyer A H,et al.A Comparative Experimental and Multiphysics Computational Fluid Dynamics Study of Coupled Surface-subsurface Flow in Bed Forms[J].Water Resources Research,2012,48(8):8 514.