Study On Dynamic Characteristics Of Open Channel Water With Rigid Vegetation

The interaction between vegetation and water flow is an important research content in aquatic ecosystems.Vegetation not only maintains the water ecosystem and its species diversity,but also has an important impact on ecological restoration,water purification,and sediment transport.In this paper,the method of combining hydraulic experiment,theoretical analysis and numerical simulation is used to discuss the hydrodynamic characteristics of the flow with submerged rigid vegetation.In the experiment,a plastic nylon rod was used to simulate rigid vegetation,and an acoustic Doppler flow meter was used to measure the water level and flow velocity.The influence of vegetation submergence and arrangement on the distribution of water level,flow velocity,energy and turbulence intensity was mainly studied.The results of the study are as follows:(1)The distribution law of water level along the way is first increase and then decrease;the same vegetation arrangement method,the difference between the highest and lowest vegetation water level decreases with the increase of submergence degree;the same submergence degree,the range of water level change and the curvature of the water surface line Both decrease with the increase of the vegetation spacing.(2)The average velocity distribution trend is gradually decreasing along the route;the same vegetation arrangement method,the difference between the maximum velocity and the minimum velocity along the route decreases with the increase of submergence;for the same submergence,the magnitude of the decrease of the velocity increases with the vegetation layout As the spacing increases,it decreases.The vertical flow velocity is divided into the upper zone,the transition zone and the bottom zone.The flow velocity in the bottom zone remains basically unchanged,the flow velocity in the transition zone increases linearly,and the flow velocity in the upper zone follows a logarithmic distribution law;the same arrangement method,the vertical velocity increases with the degree of vegetation inundation However,the increase of the velocity will decrease with the increase of the degree of vegetation submergence;for the same degree of submergence,the vertical velocity and the increase of the velocity will increase with the increase of the spacing of vegetation layout.(3)The total energy of the water flow gradually decreases along the way;the same arrangement method,the energy dissipation and the dissipation rate along the way decrease with the increase of the vegetation submergence;the same submergence,the energy dissipation and the dissipation rate along the way Both decrease with the increase of the vegetation spacing.Vertical energy distribution: the total energy provided by water flow is equal to the sum of energy dissipation and energy transfer;in the bottom area,the total energy provided by water flow is less than the dissipated energy;at the interface between vegetation and water flow,the degree of energy exchange is the most intense,and the energy consumption Both the dispersion value and the transfer value reach the maximum;in the upper free water layer,the energy dissipation is reduced,and the energy supply is greater than the energy dissipation;the same arrangement method,the intensity of energy exchange between water flows decreases with the increase of submergence.Under the same degree of submergence,the intensity of energy exchange between water flows increases with the decrease of the spacing between vegetation arrangements.(4)The turbulence intensity value of water flow shows an increasing trend in the three directions of horizontal,vertical and vertical,and vertical <horizontal <vertical;the same arrangement method,the relative turbulence intensity value decreases with the increase of submergence;With the same degree of submergence,the relative turbulence intensity value increases with the decrease of the layout distance.In this paper,ICEM is used to establish a rigid vegetation flow finite element model,and FLUENT is used to simulate the water level,velocity and vorticity distribution.The simulation results are compared with the experimental results.The results show that the simulated calculation results are in good agreement with the measured values.