Coherent Flow Structures in Open Channels

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.

List of Contributors.

Acknowledgements.

Coherent Flow Structures in Smooth–wall Turbulent Boundaary Layers: Facts, Mechnaisms and Speculations (C. Smith).

Generalized Scaling of Coherent Bursting Structures in the Near–wall Region of Turbulent Flow over Smooth and Rough Boundaries (A. Grass and M. Mansour–Tehrani).

Laboratory Observations of Particlr Entrainment into Suspension by Turbulent Bursting (M. Garcia, et al.).

Transverse Spacing of Low–speed Streaks in a Channel Flow over a Rough Bed (A. Defina).

A Model of an Impinging Jet on a Granular Bed, with Application to Turbulent, Event–driven Bedload Transport (A. Hogg, et al.).

Ratio of Lift and Shear Forces Over Rough Surfaces (A. Dittrich, et al.).

Scales of Turbulent Coherent Flow Structures in Gravel–bed Rivers (A. Roy, et al.).

Markov Analysis of Velocity Fluctuations in Gravel–bed Rivers (R. Ferguson, et al.).

The Application of Particle Image Velocimetry to the Study of Coherent Flow Structures over a Stabilizing Sediment Bed (S. Tait, et al.).

Flow Sediment Interactions in Separating Flows over Befforms (S. McLean, et al.).

The role of Coherent Structures in Developing Beforms During Sediment Transport (A. Gyr and A. Muller).

Geometrical Analysis of the Feedback Between Flow, Bedforms and Sediment Transport (A. Muller and A. Gyr).

Genesis Morphology of Erosional Shapes Associated with Turbulent Flow Over a Forward–facing Step (A. Pollard, et al.).

Coherent Flow Structures in Open–channel SLot Flow (D. Keogh and P. Addison).

Mean Flow and Turbulence Structure over Fixed Ripples and the Ripple–dube Transition (S. Bennett and J. Best).

Turbulent Sand Suspension Events: Fraser River, Canada (R. Kostaschuk and P. Villard).

Coherent Flow Structures in Squamish River Estuary, British Columbia, Canada (C. Babakaiff and E. Hickin).

Observations of Near–bed Suspended Sediment Turbulence Structures using Multifrequency Acoustic Backscattering (P. Thorne, et al).

Interaction Between Cellular Secondary Currents and Lateral Alternate Sorting (T. Tsujimoto and T. Kitamura).

Coherent Fluctuations in a Vegetated Zone of Open–channel Flow: Causes of Bedload Lateral Transport and Sorting (T. Tsujimotto).

The Structure of River Bed Relief (A. Sidorchuk).

Some Speculations on the Relation Between Channel Morphology and Channel–scale Flow Structures (G. Parker).

The Origin and Downstream Development of Coherent Flow Structures at Channel Junctions (S. McLelland, et al.).

Mean Structure of Transport–effective Flows at an Asymmetrical Confluence when the Main Stream is Dominant (B. Rhoads).

Secondary Flow and Channel Changes around a Bar in the Brahmaputra River, Bangladesh (W. Richardson, et al.).

Morphology and Stage–dependent Flow Structure in a Gravel–bed River (N. Clifford).

A Computer Model of Bank Erosion Based on Secondary Flow Simularion (A. Alabyan).

Floodplain Secondary Circulation as a Mechanism for Flow and Shear Stress Redistribution in Straight Compound Channels (P. Wormleaton).

Meandering Overbank Flow Structures (B. Willetts and P. Rameshwaran).

Flow Structure in a Large–scale Model of a Doubly Meandeering Compound River Channel (C. Naish and R. Sellin).

Linking Hydraulics, Bedload Transport and River Bed Adjustment with the Conceptual FAST Model (P. Ergenzinger and C. de Jong).

On the Origin and Effects of Large–scale Longitudinal Flow Structures in the Outer Humber Estuary (J. Hardisty, et al.).

Incoherent Structure: Turbulence as a Metaphor for Stream Braiding (C. Paola).

Index.