Experimental and Numerical Study of Free-Surface Flows in a Corrugated Pipe

Francesco Calomino,Ali Tafarojnoruz,Antonino D’Ippolito,Agostino Lauria,Roberto Gaudio,Giancarlo Alfonsi,Serena Artese

doi:10.3390/w10050638

Abstract

A new discharge computational model is proposed on the basis of the integration of the velocity profile across the flow cross-section in an internally corrugated pipe flowing partially full. The model takes into account the velocity profiles in the pressurised pipe to predict the flow rate under free-surface flow conditions. The model was evaluated through new laboratory experiments as well as a literature datasets. The results show that flow depth and pipe slope may affect the model accuracy; nevertheless, a prediction error smaller than 20% is expected from the model. Experimental results reveal the influence of the pipe slope and flow depth on the friction factor and the stage-discharge curves: the friction factor may increase with pipe slope, while it reduces as flow depth increases. Hence, a notable change of pipe slope may lead to the variation of the stage-discharge curve. A part of this study deals with numerical simulation of the velocity profiles and the stage-discharge curves. Using the Reynolds-Averaged Navier-Stokes (RANS) equations, numerical solutions were obtained to simulate four experimental tests, obtaining enough accurate results as to velocity profiles and water depths. The results of the simulated flow velocity were used to estimate the flow discharge, confirming the potential of numerical techniques for the prediction of stage-discharge curves.

Highlights

Free-surface flow in corrugated pipes is a topic of interest for culvert and drain design
The velocity values computed by the k-ω model are, in general, smaller than those computed by the k-ω SST model
The profiles simulated by both models can be considered satisfactory when compared with the experimental points

Summary

Introduction

Free-surface flow in corrugated pipes is a topic of interest for culvert and drain design. Culverts traditionally are made of large corrugated steel pipes, whose surface is corrugated because of static reasons. A correct estimation of a head loss parameter in the form of Darcy’s friction factor or Manning’s roughness coefficient is crucial for the practical design of corrugated pipes. In this context, Morris [1,2]. Was among the pioneers who made an effort to extract equations and diagrams to estimate the flow friction factor in corrugated pipes. In the past decades when his method was evaluated it could not demonstrate satisfactory predictions of friction factors, in particular for small discharges [3,4]

Methods

Results

Conclusion