3D Open Channel Flow Modeling by Applying 1D Adjustment

Document Type: Original Research Paper

Authors

1 Faculty of Civil Engineering, University College of Engineering, University of Tehran, Tehran, Iran

2 Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran,Tehran, Iran

Abstract

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 backwardfacing
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.

Keywords