This thesis concerns the occurrence of the large-scale bed and plan forms known as alternate bars and meandering, and the internal structures of the flow associated with their formation. The work is to be viewed as an extension of previous work by da Silva (1991), Yalin (1992), and Yalin and da Silva (2001). As a first step in this work, the criteria for occurrence of alternate bars and meandering of Yalin and da Silva (2001) is re-considered in view of additional field and laboratory data from the recent literature and data resulting from two series of experimental runs carried out in two sediment transport flumes. This leads to a number of modifications of the boundary-lines in the related existence-region diagram of Yalin and da Silva. The size of the largest horizontal coherent structures (HCS's) of an alternate bar inducing flow was then investigated experimentally on the basis of three series of flow velocity measurements. These were carried out in a 21m-long, 1m-wide straight channel, conveying a 4cm-deep flow. The bed consisted of a silica sand having a grain size of 2mm; its surface was flat. The measurements were carried out using a Sontek 2D Micro ADV. The horizontal burst length was found to be between five and seven times the flow width. The effect of the HCS's on the mean flow was also investigated. A slight internal meandering of the flow caused by the superimposition of burst-sequences on the mean flow was clearly detectable. Finally, with the aid of three new series of measurements in the same channel, an attempt was made to penetrate the dynamics and life-cycle of the HCS's. For this purpose, quadrant analysis was used; the cross-sectional distribution of relevant statistical turbulence-related parameters was investigated; and cross-correlations of flow velocity along the flow depth and across the channel were performed. The analysis indicates that the HCS's originate near the channel banks, with the location of ejections and sweeps being anti-symmetrically arranged with regard to the channel centreline, and then evolve so as to occupy the entire depth of the water and the entire width of the channel.

Large-Scale Simulation: Models, Algorithms, and Applications gives you firsthand insight on the latest advances in large-scale simulation techniques. Most of the research results are drawn from the authors’ papers in top-tier, peer-reviewed, scientific conference proceedings and journals. The first part of the book presents the fundamentals of large-scale simulation, including high-level architecture and runtime infrastructure. The second part covers middleware and software architecture for large-scale simulations, such as decoupled federate architecture, fault tolerant mechanisms, grid-enabled simulation, and federation communities. In the third part, the authors explore mechanisms—such as simulation cloning methods and algorithms—that support quick evaluation of alternative scenarios. The final part describes how distributed computing technologies and many-core architecture are used to study social phenomena. Reflecting the latest research in the field, this book guides you in using and further researching advanced models and algorithms for large-scale distributed simulation. These simulation tools will help you gain insight into large-scale systems across many disciplines.

This book contains the written, thoroughly reviewed versions of both invited lectures and regular presentations given at the 36th International School of Hydraulics, held at Jachranka in Poland on May 23–26, 2017. The contributions cover recent findings in the areas of mathematical modeling as well as experimental investigations related to free surface flows and pollution, sediment and heat transport processes in rivers. Better understanding of environmental flows requires cognition of physical, chemical and biological attributes of flowing water and therefore hydraulic research becomes strongly interdisciplinary field of science. The authors also realize that fundamental knowledge of environmental hydraulics problems is absolutely essential for planning and design of systems to manage water resources. Nowadays the readers face a rapid development of hydraulic research due to a boom in the computer sciences and measurement techniques and this is what this book is about. Eminent world leading experts in this field and young researchers from sixteen countries from all over the world contributed to this book.

Rivers are important agents of change that shape the Earth's surface and evolve through time in response to fluctuations in climate and other environmental conditions. They are fundamental in landscape development, and essential for water supply, irrigation, and transportation. This book provides a comprehensive overview of the geomorphological processes that shape rivers and that produce change in the form of rivers. It explores how the dynamics of rivers are being affected by anthropogenic change, including climate change, dam construction, and modification of rivers for flood control and land drainage. It discusses how concern about environmental degradation of rivers has led to the emergence of management strategies to restore and naturalize these systems, and how river management techniques work best when coordinated with the natural dynamics of rivers. This textbook provides an excellent resource for students, researchers, and professionals in fluvial geomorphology, hydrology, river science, and environmental policy.

A stream flowing in alluvium deforms its bed surface, forming ripples, dunes, bars, etc., and, in many instances, it deforms its channel entirely, thereby creating meandering or braiding patterns. It could be said that, in general, an alluvial stream and its deformable boundary undergo a variety of fluvial processes leading to the emergence of a multitude of alluvial forms. This book concerns the physics and analytical treatment of various fluvial processes and the associated alluvial bed and plan forms listed above. Following an introductory chapter on the basics of turbulent flow and sediment transport, the book covers the origin, geometric characteristics and effects of bed forms, from small- to meso-scale (ripples, dunes, alternate and multiple bars); the initiation, geometry and mechanics of meandering streams; the computation of flow, bed deformation and the planimetric evolution of meandering streams; and braiding and delta formation. The book also covers the regime concept, the time-development of a stream towards its regime state, and the formulation of stable, or equilibrium, morphology. The book distinguishes itself by its comprehensive analysis and discussion of key processes involved in large-scale river morphodynamics. The book was written primarily for researchers and graduate students of hydraulic engineering, water resources and related branches of earth sciences, but it will also prove useful for river engineers and managers.

Coherent Flow Structures in Open Channels presents the first integrated treatment, across a wide range of spatial and temporal scales, of the origins and characteristics of coherent fluid motions and their influence on sediment transport and bed morphology. This book contains contributions from an international and interdisciplinary authorship who are responsible for many of the recent advances in geophysical boundary layer research. Coherent flow structures are examined systematically across a range of scales from flat-bed boundary layers, grain and bedform roughness generated structures through to the largest scales, where structures may be associated with bars, meander bends and channel confluences. The book is broadly organized according to the spatial scales of coherent flow structures and presents a treatise on the study of these motions from theoretical, experimental and field-based approaches. These papers describe the origins, evolution and characteristics of coherent flow structures and the control which they may impart on sediment transport, both as a bed and suspended load, and ultimately on channel morphology. The book also highlights future research themes required to advance the interdisciplinary understanding of these complex, yet ubiquitous, natural flows. The research presented here will find applications within many fields, including geomorphology, sedimentology, the physical and numerical modelling of two-phase flows, environmental fluid and sediment dynamics and river engineering.