Stepped Spillways: Theoretical, Experimental and Numerical Studies

André Luiz Andrade Simões, Harry Edmar Schulz, Raquel Jahara Lobosco

and Rodrigo de Melo Porto

Source: Hydrodynamics - Natural Water Bodies
ISBN 978-953-307-893-9
Edited by: Harry Edmar Schulz, André Luiz Andrade Simões and Raquel Jahara Lobosco
Publisher: InTech, January 2012

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Hydrodynamics - Natural Water Bodies

Edited by: Harry Edmar Schulz, André Luiz Andrade Simões and Raquel Jahara Lobosco

ISBN 978-953-307-893-9, Hard cover, 286 pages
Publisher: InTech
Publication date: January 2012
Subject: Mechanical Engineering

The knowledge of the characteristics of the fluids and their ability to transport substances and physical properties is relevant for us. However, the quantification of the movements of fluids is a complex task, and when considering natural flows, occurring in large scales (rivers, lakes, oceans), this complexity is evidenced. This book presents conclusions about different aspects of flows in natural water bodies, such as the evolution of plumes, the transport of sediments, air-water mixtures, among others. It contains thirteen chapters, organized in four sections: Tidal and Wave Dynamics: Rivers, Lakes and Reservoirs, Tidal and Wave Dynamics: Seas and Oceans, Tidal and Wave Dynamics: Estuaries and Bays, and Multiphase Phenomena: Air-Water Flows and Sediments. The chapters present conceptual arguments, experimental and numerical results, showing practical applications of the methods and tools of Hydrodynamics.

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Multiphase analysis of entrained air in skimming flows along stepped chutes

H. E. Schulz, R. J. Lobosco, A. L. A. Simões

Abstract: Self-aeration is a predominant phenomenon of flows along stepped chutes. While the steps increase the energy dissipation rate, they also increase the air uptake, reducing risks of cavitation. Although aeration is a known phenomenon, a definitive quantification of the profile of the air-water mixture is still not available. This study considers the skimming flow regime, and a theoretical solution for the profile of the air-water mixture, based on the one-dimensional mass conservation equation and on a proposal for the air transfer between the atmosphere and the water. The numerical aeration of the flows along stepped chutes is investigated for chutes with uniform steps. The open softwares Salome and OpenFoam® were used  for mesh generation and CFD calculations, respectively. The flows are inherently turbulent and their characteristics were investigated here using a two equation k-e turbulence model and adequate wall functions for the wall boundaries.

University of Liège, Liège, Belgium

ACOMEN 2011 (5th Interntional Conference on Advanced Computational Methods in Engineering)

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Timeline: Stepped Spillways and Computational Fluid Dynamics

Skimming flow

TRANSITION LENGTH BETWEEN WATER AND AIR-WATER FLOWS ON STEPPED CHUTES

André Luiz Andrade Simões, Harry Edmar Schulz, Rodrigo de Melo Porto

Abstract: This study presents the steps followed to obtain mathematical models for the length of the transition region between the “full-water” and “full-mixed” flows in stepped spillways. This transition length is defined here as the distance along the flow, parallel to the pseudo-bottom, starting at the end of the “full-water” region and ending at the beginning of the “full-mixed” region. The definition is proposed based on experimental profiles of the surface obtained with an acoustic sensor in a stepped chute, which allows to locate adequately the minima and maxima of the profile. A set of profiles obtained for different flow conditions is shown, and a comparison between predicted and calculated transition lengths is made. Experimental data and theoretical predictions superpose adequately for the present set of data.

Computational Methods in Multiphase Flow VI (Link). Kos, Greece 2011.