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Résultats de la recherche (9 résultats)

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  • On large-scale flow structures in a gravel-bed river
  • Canada ; Carrying capacity ; Experimentation ; Gravel ; Quebec ; River bed ; Runoff ; Stream ; Stream flow ; Turbulence
  • This paper confirms the presence of large-scale flow structures in gravel bed rivers, pictures their sequence and patterns and characterises their mean and individual properties. The analysis relies on a new technique for displaying velocity
  • Reach scale variability of turbulent flow characteristics in a gravel-bed river
  • Canada ; Fluvial dynamics ; Gravel ; Quebec ; River bed ; Roughness ; Spatial variation ; Stream ; Turbulence
  • in the Eaton North River (Québec). At the reach scale, the distribution of individual roughness elements does not greatly control the spatial variability of turbulent flow properties.
  • Turbulence at a roughness transition in a depth limited flow over a gravel bed
  • Canada ; Fluvial processes ; Gravel ; Quebec ; River bed ; Sediment transport ; Spatial variation ; Statistics ; Stream flow ; Turbulence
  • Turbulence statistics derived from velocity measurements along a longitudinal transect characterized by a roughness transition are presented. The results describe the turbulent characteristics of the flow above a natural rough bed and also quantify
  • Three-dimensional structure of flow at a confluence of river channels with discordant beds
  • This paper presents data on the detailed structure of three-dimensional mean and turbulent flow for different hydraulic conditions at the confluence of natural rivers with discordant beds. The objectives of the paper are : 1) to describe the three
  • -dimensional field of flow at a junction of natural channels; 2) to assess the role of changes in bed morphology that occur during transport-effective events on the structure of flow at a confluence; and 3) to examine how the structure of three-dimensional flow
  • Sensitivity of bed shear stress estimated from vertical velocity profiles : the problem of sampling resolution
  • Gravel ; Methodology ; Mountain ; River bed ; Roughness ; Sand ; Shear stress ; Stream ; Stream flow ; Switzerland ; Turbulence ; Valais
  • The aim of this study is to simulate the uncertainty that arises from using the law of the wall in shallow streams, using a specific case-study to assess the extent to which estimates could be in error. More particularly, the effects on bed shear
  • stress of varying 1) the range of flow depths from which observations are obtained, and 2) the lowest elevation of a measurement point above the bed, are examined. These issues are investigated using a high vertical definition of velocity measurements
  • taken in a stream with mixed sand and gravel bed.
  • 1 min in the life of a river : selecting the optimal record length for the measurement of turbulence in fluvial boundary layers
  • This paper examines the effects of record length on the precision of turbulence statistics in fluvial boundary layers of gravel-bed rivers. From high-resolution velocity time series lasting 20 to 60 min, a bootstrapping method is used to determine
  • The application of computational fluid dynamics to natural river channels : three-dimensional versus two-dimensional approaches
  • within a gravel-bed river system with high relative roughness, are defined for each model.
  • This paper addresses the recent trend in fluvial geomorphology towards using computational fluid dynamics to explore the adjustment between flow processes, sediment transport and river channel morphology. It aims to evaluate the extent to which 3D
  • Three-dimensional measurement of river channel flow processes using acoustic doppler velocimetry
  • This paper describes and assesses : 1) the use of a new instrument for the determination of three-dimensional flow velocities in natural rivers, the acoustic Doppler velocimeter (ADV); and 2) a method for positioning and orienting such measurements
  • relative to a single local coordinate system to relate flow velocity factors with the bed and water surface. The ADV uses the Doppler shift priciple to measure the velocity of small particles , assumed to be moving at velocities similar to the fluid.
  • Bed morphology and sedimentology at the confluence of unequal depth channels
  • The field study reported here had two objectives: to describe the bed geometry at confluences of unequal depth channels and 2) to examine the relationships between bed morphology, surface sediments properties and flow dynamics as discharge varied