Journal ArticleDOI
Initial Instability of Fine Bed Sand
TLDR
In this paper, the initial entrainment characteristics of fine bed sand are objectively defined in terms of the measured distributions of critical instantaneous bed shear stress associated with the observed movement of individual surface grains.Abstract:
The initial entrainment characteristics of fine bed sand are objectively defined in terms of the measured distributions of critical instantaneous bed shear stress associated with the observed movement of individual surface grains. Critical flow conditions are then predicted by equating the lower extremes in these characteristic critical shear stress distributions to the upper extremes in the distribution of instantaneous bed shear stress produced by the particular type of background flow under consideration. The method is applied to the case of two-dimensional channel flow over a flat bed and yields sufficiently consistent results to suggest an extension to Shields' curve for small grain Reynolds numbers. The detailed experimental observations clearly illustrate the important role played by bed region turbulence in the interaction process between the fluid and the mobile bed grains constituting the deformable boundary.read more
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Journal ArticleDOI
Calculating the explicit probability of entrainment based on inertial acceleration measurements
Georgios Maniatis,Trevor Hoey,Marwan A. Hassan,Joseph Sventek,Rebecca Hodge,Timothy D. Drysdale,Manousos Valyrakis +6 more
TL;DR: In this article, a new method for the approximation of the explicit probability of entrainment for individual coarse particles is presented, which is based on the derivation of inertial acceleration measurements, space-state approximation, and the probabilistic approximation for the threshold acceleration that causes incipient motion.
Journal ArticleDOI
Critical Bed Shear Stress for Unisize Sediment
Oscar A. Sarmiento,Marco Falcón +1 more
TL;DR: In this paper, the authors derived the instantaneous, critical shear-stress parameters required for incipient motion of uniform-sized sand grains, independent of the bed shear velocity particle Reynolds number, equal to 0.16, from calibration of a theory for bed load sediment transport, by minimizing the sum of the squares of the deviations between theoretical and experimental bed load rates.
Book ChapterDOI
Entrainment Threshold of Loose Boundary Streams
TL;DR: In this paper, the important laboratory experimental and theoretical studies on threshold of sediment entrainment under steady stream flows are briefly summarized, as a perspective review, highlighting the empirical formulations and semitheoretical analyses.
Journal ArticleDOI
Remote sensing for optimal estimation of water temperature dynamics in shallow tidal environments
Mattia Pivato,Luca Carniello,Daniele Pietro Viero,Chiara Soranzo,Andrea Defina,Sonia Silvestri +5 more
TL;DR: An integrated approach for water temperature monitoring in a shallow lagoon is developed which incorporates satellite and in-situ data into a mathematical model and is used to constrain large-scale patterns of water temperature and high-frequency in situ observations to provide proper time constraints.
Journal ArticleDOI
Parameterisation of clastic sediments including benthic structures
TL;DR: In this article, the sediment transport processes in the south-western Baltic Sea are predicted by means of a numerical model in the project DYNAS, and two sediment parameters that influence the results of modelling remarkably: critical shear stress velocity and bottom roughness.