Transient Flow in an Open Channel Bound by Two Step Pumping Stations

Ibrahim Ibrahim,Xiaoli Feng,Baoyun Qiu

doi:10.3390/w10040502

Abstract

Pumping stations play a great role in open channel flow applications. After starting pump units in the pumping stations, unsteady flows in the open channel are immediately generated. In this paper, the behavior of unsteady flow in a prismatic trapezoidal channel between two step pumping stations is studied. A mathematical model is constructed to simulate one-dimensional, unsteady, gradually-varied open channel flow in the channel. The soil leakage and evaporation from the water surface along the channel are also involved. The Lax diffusive scheme is applied to solve the proposed model. The model is applied on a real open channel located in China. The accuracy of the model is calculated by varying the scheme grid steps. We also calculate and discuss the water surface elevation, the flow rate and the lateral outflow per unit length, as well as several influential factors at various stages along the channel. In this work, the wave propagation mechanism is clearly presented and analyzed. The computed results show that the water surface profile in the open channel varies continuously over time until it becomes almost constant. Thus, the pumping station operation duties change over time. The accuracy of the results is validated by comparing the computed results with measured data.

Highlights

The study of open channels is an important topic involving hydraulics and hydrology
A wide range of numerical schemes based on the finite difference [6,7,8,9,10,11], finite element [12,13,14], and finite volume [15] methods have been applied to solve the open channel flow equations
To study the unsteady flow behavior in an open channel between two pumping stations, we considered a prismatic trapezoidal channel bound by Huai’an and Huaiyin pumping stations in Jiangsu Province, China

Summary

Introduction

The study of open channels is an important topic involving hydraulics and hydrology. The flow conditions in real-life systems usually vary with time, and the flows are unsteady. The governing hydraulic equations, known as the Saint-Venant equations, are derived from the incompressible Navier–Stokes equations [1,2] which consist of continuity and momentum equations [3] These equations are nonlinear, first-order, hyperbolic, partial differential equations for which closed-form solutions are not available, except for under certain simplified conditions; these equations are solved using suitable numerical techniques [4,5]. We considered a prismatic trapezoidal channel bound by Huai’an pumping. We considered a prismatic trapezoidal channel bound by Huai’an pumping station (Figure 2) and Huaiyin pumping station (Figure 3) in Jiangsu Province, China. Huai’an pumping station is located at the intersection of the Grand Canal and Northern Jiangsu. It has been appraised as a high-quality project in the province

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Conclusion