TY - JOUR

T1 - Using Lagrangian particle saltation observations for bedload sediment transport modelling

AU - Niño, Yarko

AU - Garcia, Marcelo Horacio

PY - 1998/6/30

Y1 - 1998/6/30

N2 - A Lagrangian model for the saltation of sand in water is proposed. Simulated saltation trajectories neglecting particle rotation and turbulence effects compare fairly well with experimental observations. The model for particle motion is coupled with a stochastic model for particle collision with the bed, such that a number of realizations of the saltation process can be simulated numerically. Model predictions of mean values and standard deviations of saltation height, length and streamwise particle velocity agree fairly well with experimental observations. Model predictions of the dynamic friction coefficient are also in good agreement with experimental observations, but they underestimate the value of 0.63 proposed by Bagnold for this coefficient. The saltation model is applied to the estimation of bedload transport rates of sand using a Bagnoldean formulation. Modelled values of the bedload transport rates overestimate those predicted by commonly used bedload formulae, which appears to be a consequence of problems in the definition of the dynamic friction coefficient. These results seem to indicate a few problems with the Bagnoldean formulation, particularly regarding the continuum assumption for the bedload layer, which would be valid only for very high particle concentrations and small particle diameters, and also regarding the evaluation of the shear stress exerted on the bed by the saltating particles.

AB - A Lagrangian model for the saltation of sand in water is proposed. Simulated saltation trajectories neglecting particle rotation and turbulence effects compare fairly well with experimental observations. The model for particle motion is coupled with a stochastic model for particle collision with the bed, such that a number of realizations of the saltation process can be simulated numerically. Model predictions of mean values and standard deviations of saltation height, length and streamwise particle velocity agree fairly well with experimental observations. Model predictions of the dynamic friction coefficient are also in good agreement with experimental observations, but they underestimate the value of 0.63 proposed by Bagnold for this coefficient. The saltation model is applied to the estimation of bedload transport rates of sand using a Bagnoldean formulation. Modelled values of the bedload transport rates overestimate those predicted by commonly used bedload formulae, which appears to be a consequence of problems in the definition of the dynamic friction coefficient. These results seem to indicate a few problems with the Bagnoldean formulation, particularly regarding the continuum assumption for the bedload layer, which would be valid only for very high particle concentrations and small particle diameters, and also regarding the evaluation of the shear stress exerted on the bed by the saltating particles.

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U2 - 10.1002/(SICI)1099-1085(19980630)12:8<1197::AID-HYP612>3.0.CO;2-U

DO - 10.1002/(SICI)1099-1085(19980630)12:8<1197::AID-HYP612>3.0.CO;2-U

M3 - Article

AN - SCOPUS:0032581027

SN - 0885-6087

VL - 12

SP - 1197

EP - 1218

JO - Hydrological Processes

JF - Hydrological Processes

IS - 8

ER -