Two-Dimensional Finite-Element Hydraulic Modeling of Bridge Crossings. Research Report

摘要

The report presents the results of a 6-year project, conducted by the U.S. Geological Survey in cooperation with the Federal Highway Administration (FHWA), to develop an accurate, efficient, easy-to-use finite-element surface-water flow model (FESWMS-2DH) for use in analyzing backwater and flow distribution at highway crossings of rivers and flood plains. When lateral variations in water-surface elevation and flow distribution are significant, a two-dimensional approach has advantages over a one-dimensional approach. The finite-element method is ideally suited to modeling two-dimensional flow over complex topography with spatially variable roughness and allows the user great flexibility in defining flow boundaries, channels, and embankments. A large number of alternative flow-equation formulations, interpolation and weighting functions, and schemes for solving the large systems of algebraic equations that arise in applying the finite-element method were tested during the project. Features added to FESWMS-2DH include weir flow (roadway overtopping), culvert flow, linear variation of Manning's n with depth, simple and accurate handling of lateral boundaries, automatic network generation and refinement, and extensive error checking.