نتایج جستجو برای: bed boundary

تعداد نتایج: 207726  

2017
Charles J. Lemckert

This study describes a new convenient and robust system developed to measure benthic boundary layer properties, with emphasis placed on the determination of bed shear stress and roughness height distribution within estuarine systems by using velocity measurements. This system consisted of a remotely operated motorised traverser that allowed a single ADV to collect data between 0 and 1 m above t...

Journal: :journal of water sciences research 2010
s.h ghoreishi m.r majdzadeh tabatabai

sediment flushing of reservoirs is an operational technique, whereby previously accumulated sediments in the reservoirs are hydraulically removed by accelerated flow when the bottom desiltingoutlets of the dam are opened. in this research, the process of sediment flushing is simulated by a three dimensional numerical model in which sediment and flow interaction are reflected in the reservoirs. ...

2011
Jeffrey A. Nittrouer David Mohrig Mead Allison

[1] Measurements of sand flux and water flow in the Mississippi River are presented for a portion of the system 35–50 km upstream from the head of its subaerial delta. These data are used to provide insight into how nonuniform flow conditions, present in the lower reaches of large alluvial rivers, affect the timing and magnitude of sand transport near the river outlet. Field surveys during both...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2015
Abram H Clark Mark D Shattuck Nicholas T Ouellette Corey S O'Hern

We performed molecular dynamics simulations of granular beds driven by a model hydrodynamic shear flow to elucidate general grain-scale mechanisms that determine the onset and cessation of sediment transport. By varying the Shields number (the nondimensional shear stress at the top of the bed) and particle Reynolds number (the ratio of particle inertia to viscous damping), we explore how variat...

1993
THOMAS E. LISLE

Gravel bed channels have a much greater capacity than sand bed channels to regulate the mobility of the bed surface through the formation of a surface layer of bed particles that is coarser than the particles supplied as load. The coarse surface layer affects bed mobility in two important ways. First, it reduces differences in mobility between coarser and finer particles on the bed surface by m...

2007
C. Ryu S. Choi

CFD analysis on the MSW incinerator combustion chamber provides crucial insight on the thermal flow fields, but a difficulty arise from the boundary conditions on the waste bed in which the combustion is governed by complicated heat and mass transfer phenomena. Solid waste bed combustion models are constructed to predict the combustion process and corresponding generation of gas phase species b...

2002
L. Collins

Bed surface particle size patchiness may play a central role in bedload and morphologic response to changes in sediment supply in gravel-bed rivers. Here we test a 1-D model (from Parker ebook) of bedload transport, surface grain size, and channel profile with two previously published flume studies that documented bed surface response, and specifically patch development, to reduced sediment sup...

Journal: :The American naturalist 2011
Megan J Donahue Robert A Desharnais Carlos D Robles Patricia Arriola

Ecological thresholds are manifested as a sudden shift in state of community composition. Recent reviews emphasize the distinction between thresholds due to phase shifts-a shift in the location of an equilibrium-and those due to alternative states-a switch between two equilibria. Here, we consider the boundary of intertidal mussel beds as an ecological threshold and demonstrate that both types ...

2005
W. E. Dietrich P. A. Nelson E. Yager J. G. Venditti

Bed surface particle size patchiness may play a central role in bedload and morphologic response to changes in sediment supply in gravel-bed rivers. Here we test a 1-D model (from Parker ebook) of bedload transport, surface grain size, and channel profile with two previously published flume studies that documented bed surface response, and specifically patch development, to reduced sediment sup...

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