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Showing 1 to 20 of 20 for “"incipient motion"”.
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Incipient Motion Under Shallow Flow Conditions
… Shields diagram cannot be used to predict the incipient motion of coarse sediment particles when the relative depth is below 10 and the Froude number is above 0.5, approximately. Experiments using glass balls, whose density is almost identical to that of natural gravel, show that the Shields …
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Incipient motion of mixed sediment load on the Rio Chama
… of this study were to spatially evaluate incipient motion of sediments for environmental flows and to determine the flow required to mobilize the channel bed. To accomplish the objective, topographic data collected at the Archuleta and Cebolla sites was used to develop a 2-D mesh in …
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Experimental Investigation of the Role of Turbulence Fluctuations on Incipient Motion of Sediment
… transport, usually referred to as threshold of motion or critical condition, is even more challenging due to the highly fluctuating nature of turbulent flow. Numerous works have advocated that the peak turbulent forces, randomly occurring in time and space with magnitudes higher than the …
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Hydraulic Characterization of Mounded Gravel Fish Nests: Incipient Motion Criteria and Despiking Acoustic Doppler Velocimeter Data
… seeks to apply sediment transport models to find incipient motion criteria and erosion susceptibility of chubs nests. Field water flow velocities were measured with an acoustic Doppler velocimeter (ADV) in Tom's Creek, Blacksburg, Virginia, USA. ADVs are often used to collect in-situ turbulent …
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Experimental investigation of the impact of the permeable layer thickness on the surface flow above and the threshold for incipient motion of submerged objects
… understood. Current models for threshold of incipient motion implicitly assume an impermeable rough bed when evaluating the fluid forces exerted on submerged objects. Natural river beds are permeable and the impact of the presence of bed permeability or the thickness of the permeable bed on …
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A computational fluid dynamics model for sediment movement based on the unit stream power approach
… stream power approach is employed to define the incipient motion criteria for the sediment particles by comparing the available applied stream power with the individual particle power requirements for motion (Rooseboom 1992). The Movability Number (Lui 1957), which represents the shear …
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Mechanics of Sandbag Motion In Free-Surface Flow
… application and research on the mechanics of motion of sandbag needed to optimize their placement are limited. The problem of the motion of sandbags in open-channel flow is complex since the sandbag shape varies from a very flat hump to spherical, sandbags may be porous and permeable, and the …
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The Role of Turbulence on the Entrainment of a Single Sphere and the Effects of Roughness on Fluid-Solid Interaction
Incipient motion criterion in sediment transport is very important, as it defines the flow condition that initiates sediment motion, and is also frequently employed in models to predict the sediment transport at higher flow conditions as well. In turbulent flows, even a reasonably accurate …
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The Role of Instantaneous Forces in Particle Movement
… shear stress is determined by the point of incipient motion. Researchers have attempted to predict bed load transport both deterministically with mean parameters and stochastically attempting to take into account the fluctuations of velocity at points near threshold. This work attempts to …
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SAMPLING AND MODELING OF SEDIMENT TRANSPORT AND RESERVOIR EROSION FOLLOWING DAM REMOVAL: MILLTOWN DAM, MONTANA
… and in suspension with different thresholds for incipient motion between the confined Blackfoot and unconfined alluvial Clark Fork Arms of the reservoir. Bedload sediments, gravel and larger sized, transported downstream as a dispersing and translating wave. Sediment budget calculations, both …
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SAMPLING AND MODELING OF SEDIMENT TRANSPORT AND RESERVOIR EROSION FOLLOWING DAM REMOVAL: MILLTOWN DAM, MONTANA
… and in suspension with different thresholds for incipient motion between the confined Blackfoot and unconfined alluvial Clark Fork Arms of the reservoir. Bedload sediments, gravel and larger sized, transported downstream as a dispersing and translating wave. Sediment budget calculations, both …
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Experimental study of internal gravity waves over a slope
… frequency. Measurements of the wave motion in the fluid interior were primarily taken with electrical conductivity probes; measurements in the boundary layer were made with dye streaks and neutrally buoyant particles. The results indicate that, outside of the breaking zone, the …
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Channel Migration and Bank Erosion of the Clark Fork River at Grant-Kohrs Ranch N.H.S., Western Montana
… count were conducted along each segment. An Incipient Motion Method was used to determine at which discharge motion would begin. From the record of flow, and cross section analyses, results indicate that it is the moderate flow events which are responsible for the sediment transport regime …
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Channel Migration and Bank Erosion of the Clark Fork River at Grant-Kohrs Ranch N.H.S., Western Montana
… count were conducted along each segment. An Incipient Motion Method was used to determine at which discharge motion would begin. From the record of flow, and cross section analyses, results indicate that it is the moderate flow events which are responsible for the sediment transport regime …
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Abrasion, transport and distribution of sediment in selected streams of Southern Ontario and Western New York /
… approximated by Baker and Ritter's equation. Incipient motion of blocks in Twenty Mile Creek is best predicted by Yalin's relation which is more efficient in deeper flows. The transport distance of blocks in both streams depends on channel roughness and geometry. Natural abrasion and …
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Determination of Optimal Stable Channel Profiles
… composed of particles that are all in a state of incipient motion. It is the combination of this channel geometry and the phenomenon of momentum-diffusion, that allows the present model to simulate the "stable bank, mobile bed" condition observed in rivers. The coupled equations of …
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Energetics of Turbulence Explains Physical Transport Processes in the Environment
… extends the co-spectral budget model to link the incipient motion of sediments to turbulent eddies. A mathematical derivation is presented to elucidate the scaling properties of an empirical diagram between a densimetric Froude number and relative roughness, connecting sediment motion to turbulent …
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Initiation of Particle Movement in Turbulent Open Channel Flow
… that lead to coarse grain entrainment at near incipient motion conditions. Herein, a new conceptual approach is proposed, which in addition to the magnitude of hydrodynamic force or flow power, takes into account the duration of the flow event. Two criteria for inception of grain entrainment, …
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The Role of Turbulence on the Initiation of Sediment Motion
… study examines the role of turbulence on the incipient motion of sediment. For this purpose, well-controlled experiments are performed at the laboratory in a tilting flume. In these tests glass beads of the same size and density are used as the testing material to isolate the role of …
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Geotechnical Investigation and Characterization of Bivalve-Sediment Interactions
… require a flow velocity of at least 1.7 m/s for incipient motion of the boulder-sized riprap. In addition to the contiguous living bivalve mat offering scour protection, the whole or fragmented shells (i.e., shell hash) that are left behind from dead bivalves are hypothesized to reduce erosion …