Flow Topology in the Confluence of an Open Channel with Lateral Drainage Pipe

Mohammad Nazari-Sharabian,Donald Hayes,Moses Karakouzian

doi:10.3390/hydrology7030057

Mohammad Nazari-Sharabian, Donald Hayes + Show 1 more

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https://doi.org/10.3390/hydrology7030057

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Abstract

The purpose of this paper is to develop design guidelines for flood control channel height in the vicinity of the confluence of a submerged drainage pipe and a flood control channel. The water exchange in the confluence of an open channel with a lateral drainage pipe produces unique hydraulic characteristics, ultimately affecting the water surface elevation in the channel. An accurate prediction of the water surface elevation is essential in the successful design of a high-velocity channel. By performing several experiments, and utilizing a numerical model (FLOW-3D), this study investigated the impact of submerged lateral drainage pipe discharges into rectangular open channels on flow topology in the confluence hydrodynamics zone (CHZ). The experiments were conducted in different flume and junction configurations and flow conditions. Moreover, the simulations were performed on actual size channels with different channel, pipe, and junction configurations and flow conditions. The flow topology in the CHZ was found to be highly influenced by the junction angle, as well as the momentum ratios of the channel flow and the pipe flow. The findings of this study were used to develop conservative design curves for channel confluences with lateral drainage pipe inlets. The curves can be used to estimate water surface elevation rise in different channel and pipe configurations with different flow conditions to determine the channel wall heights required to contain flows in the vicinity of laterals.

Highlights

Confluences of open channels and lateral drainage pipes are important elements in the hydraulic networks of man-made canals [1]
Flow through lateral drainage pipes to open channels impacts channel capacity and disrupts the natural flow of water by creating turbulence in the vicinity of the inlet pipe, as well as influencing flow characteristics in the confluence hydrodynamics zone (CHZ) (Figure 1). Even though these confluences represent a critical component of drainage system geometry, they have received surprisingly little attention from researchers and engineers
This is mainly due to the relatively large number of parameters involved, along with the complex flow features occurring in the CHZ [3]

Summary

Introduction

Confluences of open channels and lateral drainage pipes are important elements in the hydraulic networks of man-made canals [1] They are necessarily encountered at the end of urban sewage or agricultural subsurface drainage networks, where they release water [2]. Flow through lateral drainage pipes to open channels impacts channel capacity and disrupts the natural flow of water by creating turbulence in the vicinity of the inlet pipe, as well as influencing flow characteristics in the confluence hydrodynamics zone (CHZ) (Figure 1). Even though these confluences represent a critical component of drainage system geometry, they have received surprisingly little attention from researchers and engineers. No comprehensive data set has been compiled that describes the 3D flow field within the CHZ [4]

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