Results 211 to 220 of about 158,311 (260)
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ON BED FORMS AND PALAEOCURRENTS
Sedimentology, 1966SUMMARYBed forms arise by interaction between a fluid flow and the sediment transported over or close to the bed. The geometry of bed forms is two‐dimensional or three‐dimensional. Two‐dimensional bed forms generate two‐dimensional internal sedimentary structures and are adjusted to two‐dimensional flow‐vector fields.
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Bed load transport by bed form migration
Acta Geophysica, 2012A theoretically-based methodology is presented for the determination of bed load transport from high-resolution measurements of bed surface elevations for steady-state or developing dunes. The methodology is based on the general form of the Exner equation for sediment continuity and requires information on the distribution of sediment volume ...
Jochen Aberle +2 more
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Bed form initiation from a flat sand bed
Journal of Geophysical Research: Earth Surface, 2005Bed form initiation in unidirectional flow is examined on a flat bed composed of a homogeneous 0.5 mm sand. Velocity profiles taken prior to bed form development indicate that the examined flows are typical of fully turbulent, uniform, open channel flows.
Jeremy G. Venditti +2 more
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2009
Aeolian bedforms range in size from small-scale (ripples), through medium-scale (dunes) to large-scale (megadunes or draa). This chapter describes the physical characteristics and development of each of these bedform types, including their relationship to airflow and sand transport at different spatial and temporal scales.
Kenneth Pye, Haim Tsoar
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Aeolian bedforms range in size from small-scale (ripples), through medium-scale (dunes) to large-scale (megadunes or draa). This chapter describes the physical characteristics and development of each of these bedform types, including their relationship to airflow and sand transport at different spatial and temporal scales.
Kenneth Pye, Haim Tsoar
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1999
The movement of sediments as bed load and suspended load usually refers to their movement as individual particles. Yet while sediment is being transported, the bed load particles move collectively in all sorts of ways along the river bed. Their motion in tum can cause changes in the configuration of the river bed in accordance with the variation of ...
Ning Chien, Zhaohui Wan
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The movement of sediments as bed load and suspended load usually refers to their movement as individual particles. Yet while sediment is being transported, the bed load particles move collectively in all sorts of ways along the river bed. Their motion in tum can cause changes in the configuration of the river bed in accordance with the variation of ...
Ning Chien, Zhaohui Wan
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Bed-Form Geometry in Sand-Bed Flows
Journal of Hydraulic Engineering, 1999A new method is proposed for predicting relative bed-form height h/d in sand-bed flows. The proposed method is based on the concept of relating energy loss due to form drag to the head loss across a sudden expansion in open channel flows. A unique feature of the proposed method is that it can be applied to various bed forms, i.e., ripples, dunes ...
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Role of Near‐Bed Turbulence Structure in Bed Load Transport and Bed Form Mechanics
Water Resources Research, 1995The interactions between turbulence events and sediment motions during bed load transport were studied by means of laser‐Doppler velocimetry and high‐speed cinematography. Sweeps (u′ > 0, w′ < 0) which contribute positively to the mean bed shear stress, collectively move the majority of the sediment, primarily because they are extremely common ...
Jonathan M. Nelson +3 more
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Bed forms in turbulent channel flow
Applied Mechanics Reviews, 2004Bed forms in channels result from the interaction between sediment transport, turbulence and gravitational settling. They document mechanisms of self-organization between flow structures and the developing structure of the bed. It is shown that these mechanisms can be characterized by length scales of the sediment, the bed form and the flow structure ...
Gyr and, Albert, Kinzelbach, Wolfgang
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Three-dimensional river bed forms
Journal of Fluid Mechanics, 2012AbstractThe linear stability of a uniform flow in an infinitely wide erodible channel is investigated with respect to disturbances of the bed that are periodic in both the transverse and the longitudinal directions. A rotational flow and sediment transport model, originally developed to study the formation of two-dimensional dunes and antidunes, is ...
COLOMBINI, MARCO ENRICO +1 more
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Modelling Dynamic Bed Roughness Associated with Bed Form Development
2009In this study bed form development was quantified and used to calculate a dynamic bed roughness parameter. An algorithm that can be readily implemented into numerical models was developed and evaluated for two scenarios, with distinct flow conditions and sediment carrying capacities.
W B Rauen, B Lin, R A Falconer
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