신항만부지에서의 유동 및 수질에 관한 유한요소해석

Abstract

Water flow simulations for environmental problems often require local detailed analyses for better understanding and accurate prediction of the fate of pollutant in water bodies. This study deals with the development and application of a two-dimensional flow and dispersion model to the coastal water area to find out possible changes due to the wide port development plan. The model uses finite element theory and the Galerkin weighted-residual approach as its basis. As far as the spatial discretization is concerned, the finite element method is attractive because of its flexibility and ability to naturally treat complex coastal geometries.

The water area is discretized into linear, triangular elements. Boundary conditions of the Dirichlet and Neumann type are applied. A third type(Robin) boundary condition can be applied where river flow exits along the coastline. In order to describe long and relatively slow transients, such as those related to pollutant dispersion, the use of explicit two-step time stepping methods is introduced into the model formulation.

Two submodels, the flow induced circulation model and pollutant dispersion model, are tested by comparing with the analytical solution in a rectangular harbor where its analytical solutions are known. The tested results are of well agreement with the analytical solutions. The model is applied to Busan New Harbor area to simulate circulation and pollutant dispersion in terms of construction steps for coastal dikes. Effects of the sequential construction coastal dikes which change coastline configurations and separation of water bodies are necessary to be investigated and predicted in terms of flow and water quality.

Results from the model were compared with the measured water level and flows in four stations. The flow pattern by the model shows to be similar to the observed data away from the construction site where the flow is not affected. From the simulation results, it is concluded that the model may be useful for numerous other studies for planning and management purposes, especially flow and pollution dispersion in the coastal water bodies where the flow is so complicated.