3D Open Channel Flow Modeling by Applying 1D Adjustment

A three-dimensional (3D) finite volume model with a novel adjustment scheme was developed to solve shallow water equations in open channels. An explicit finite volume method was used to discretize the governing equations in a boundary-fitted structured and collocated grid system. Because a simple second-order central scheme was used for spatial discretization and due to the occurrence of high Peclet numbers in open channel flows, some treatments were needed to reduce oscillation. Thus, a special adjustment scheme designed to minimize differences in the averaged free surface elevation and flow discharge in a 3D model and 1D flow data was applied to some cross-sections. The model was applied to simulate shallow water flow in a backward- facing step, a meandering channel with 90° bends and a 180° bend channel. A comparison of the model results with available experimental and numerical data illustrated that the proposed numerical procedure decreases the numerical oscillations and increases the stability of the 3D numerical model in open channel flow modeling.