Numerical assessment of the inception point in different stepped spillway configurations
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ORIGINAL PAPER
Numerical assessment of the inception point in different stepped spillway configurations Anouar Kaouachi 1 & Rita F. Carvalho 2,3 & Saâdia Benmamar 4 & Mustapha Gafsi 1 Received: 31 May 2018 / Accepted: 22 August 2019 # Saudi Society for Geosciences 2019
Abstract Many studies on several aspects of the flow characteristics over a stepped spillway such as air entrainment, velocity profiles, and energy dissipation were mostly based on physical models and more recently with computers flagrant revolution on CFD. This latter presents clear advantage as reducing laboratory testing which leads to time optimization, and cost reducing. However, CFD is not still accepted without careful validation and verification. The aim of this article is to show the reliability of numerical modeling through results of k-ɛ RNG turbulence model and using volume of fluid (VOF) method to achieve inception point location. Different stepped spillway configurations were simulated with two different slopes (14° and 26.6°) and different step heights for a large range of flows. The results on velocities profiles obtained by the numerical simulations were in accordance with experimental data, which allowed the analysis of inception point location that fits experimental results as well as the empirical formulas presented by different researchers. A methodology to achieve inception point, based on CFD, is presented, verified, and validated, contributing to the acceptation of CFD. Keywords Stepped spillway . Inception point . Physical model . CFD . VOF . Turbulence model k-ɛ RNG
Introduction Stepped spillways are known since at least 3500 years ago (Chanson 2001). The renewed interest in it was associated with the development of new construction materials, as the roller-compacted concrete (RCC) (Chanson and Toombes 2001). Stepped spillways became a current method for discharging flood waters, as the steps greatly increase energy dissipation through its path and thereby reducing the stilling basin size downstream the spillway. Furthermore, it has an
advantage of easy construction and maintenance. However, their hydraulic behavior is complicated, which led to many studies and research on flows aiming to settle the geometry for an optimized operation and exploitation (Frizell and Svoboda 2012). Researchers have been striving to improve the process of discharge and based on physical models and developed technology and equipment have enhance flow patterns and shown that stepped spillways increase air entrainment performance and energy dissipation compared with smooth profile spillway (Rajaratnam 1990; Chanson 1994;
Editorial handling: Domenico M. Doronzo * Anouar Kaouachi [email protected] Rita F. Carvalho [email protected]
1
Research Laboratory of Water Resources, Soil and Environment, Department of Civil Engineering, Faculty of Civil Engineering and Architecture, Amar Telidji University, Boulevard of the Martyrs, P.O. Box 37.G, 03000 Laghouat, Algeria
2
MARE - Marine and Environmental Sciences Centre, Faculty of Sciences and
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