Improvement of 2-D Finite Element Model Using Analysis of Initial Water Surface Elevation

Abstract Initial condition of water surface elevation with boundary condition is required to simulate two-dimensional finite elementmodel. In general, in order to perform two-dimensional finite element model, unrealistic initial water surface elevation which isabove all-terrain bed elevation and unmatched downstream boundary condition is used, which will make it difficult to perform sta-bly. In this study, the water surface elevation caused by the actual river bed rather than a fixed value is applied automatically as theinitial condition of a two-dimensional finite element model. The algorithm to automatically extract river cross section for sim-ulation of one-dimensional hydraulic analysis from a two-dimensional element mesh is developed. And the accuracy of two-dimensional model tried to upgrade by improving the two-dimensional finite element model, which used the results of one-dimen-sional non-uniform analysis as the initial condition of two-dimensional model. To examine the applicability of an improved model,the model was applied to the rectangular channel with a rapid slope, mild-steep slopes channel, steep-mild slopes channel and HanRiver. The results of the model, which the initial water surface elevation of one-dimensional flow analysis is used, were more sta-bly converged than those of existing model and the stability of numerical computation was improved by using physical initialwater surface elevation. Key words : Finite element model, Initial condition, Initial water surface elevation, 2D mesh