The numerical simulation of pollutant mixing zone from riverside discharge outlet in Three Gorges Reservoir

摘要

A new numerical model, which is called non-horizontal multi-layer finite element method, is developed in this paper. The quadrilateral finite elements are employed in every layer for easy adaptation to complex boundary configuration. It is shown that the good solution can be obtained due to dealing well with the variation of water free surface along the river, the complex riverside and underwater topography. A case study for a steady flow in a bend channel shows that numerical results are verified well by experimental data. The model is also verified by the field surveying data of the velocity and concentration near a side discharge outlet before the Three Gorges Reservoir is formed. Furthermore, the characteristics of flow and pollutant mixing zone of a typical discharge in the Three Gorges Reservoir are also simulated by this method. With comparison of the pollutant mixing zone before and after the Reservoir is formed, the change tendency of the mixing zone in different water elevations is figured and the impacts of the Three Gorges Project on the pollutant mixing zone in the Reservoir is discussed.