3D Numerical Modeling Of Flow And Pollutant Convection-Diffusion Of Vegetated Channel

Recently the wetlands beside the rivers have attracted a extensive attention all over the world. The construction of ecological river is spring up rapidly around the world. Vegetations are widely distributed in the wetlands and used on the construction of ecological river. The effects of vegetation on the flow pattern and material transportation have drawn numerous scholars' great interest.The vegetations in the nature are variety. The paper studies the effect of submerged rigid vegetations on the flow, which don't incline and sway in the flow. The 3D model of flow and pollutant convection-diffusion of vegetated channel was built on the base of the k-εdouble equations' turbulence model in non-orthogonal curvilinear coordinates studied before. The vegetations' drag force and the work done by the force were induced to draw the effect of vegetation on the flow.With the 3D model of flow of vegetated channel we computed the velocity, Reynold stress on the x-z plane and the longitudinal turbulence intensity of channel with submerged vegetations. We analyzed the effect of vegetated density on the velocity, Reynold stress on the x-z plane and the longitudinal turbulence intensity, and compared with the experimental results.Most natural rivers are meandering. The flow in the curved channels has themselves special characteristics. The same as the different schemes in the construction of ecological river, the paper simulated the flow in three different vegetation arrangements, which the vegetations were planted in the inner bank, central of channel and outer bank. We computed the mean velocity and secondary flow, and compared with the experimental results.The hydrophytes can purify water body. The vegetations in the flow would affect pollutant movement. The paper simulated the convection and diffusion of pollutant through the submerged vegetations, analyzed the effect of vegetation on the pollutant vertical distribution and longitudinal transportation, and compared with experimental results. In addition the paper studied the changing of pollutant convection and diffusion before and after vegetated.The computational results of our model were in satisfactorily agreement with the experimental results, which showed the validity of the models in the paper. And the phenomena of flow and the principle of pollutant convection-diffusion through vegetations from the paper were valuable reference, which could provide the theoretical foundation for the management of river wetlands, the construction of ecological river and the pollution treatment projects.