Bose, Sujit K. ; Dey, Subhasish (2013) Sediment entrainment probability and threshold of sediment suspension: exponentialbased approach Journal of Hydraulic Engineering, 139 (10). pp. 10991106. ISSN 07339429

PDF
 Author Version
443kB 
Official URL: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29H...
Related URL: http://dx.doi.org/10.1061/(ASCE)HY.19437900.0000763
Abstract
This study examines the probability for sediment entrainment to bed load and the probability for the threshold condition of sediment to be in suspension. The theoretical analysis is based on a simple onesided exponential distribution of probability function. The probability distributions are derived from a truncated universal GramCharlier series expansion based on the exponential or Laplacetype distributions for turbulent velocity fluctuations. The key criterion of sediment entrainment is the hydrodynamic lift acting on a solitary particle to exceed submerged weight of the particle. In this way, a simple probability function for sediment entrainment to bed load in terms of Shields parameter containing the lift coefficient is obtained. It was found that the value of lift coefficient as 0.15 satisfactorily fitted the probability function versus Shields parameter curve with the experimental data. On the other hand, the key criterion of the threshold of sediment sus pension is the fluctuations of the vertical velocity component to exceed terminal fall velocity of the particle. The probability function for the threshold of a sediment particle to be in suspension is obtained in terms of Shields parameter as a function of shear Reynolds number. Curves for different values of probabilities are drawn in respect to a Shields diagram. For the value of probability 0.05, the threshold of sediment suspension is indicated. The prediction curves for the threshold of sediment suspension are proposed in terms of Rouse number versus Shields parameter and also Shields parameter versus shear Reynolds number.
Item Type:  Article 

Source:  Copyright of this article belongs to American Society of Civil Engineers. 
Keywords:  Bed Loads; Fluvial Hydraulics; Open Channel Flow; Probability Density Functions; Sediment Transport; Streamflow; Suspended Loads; Turbulent Flow 
ID Code:  97820 
Deposited On:  11 Nov 2013 06:08 
Last Modified:  19 May 2016 09:55 
Repository Staff Only: item control page