Author(s): Marco Pilotti; Giovanni Menduni

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Abstract: In this paper the main results of an experimental investigation on the beginning of sediment transport of incoherent granular materials in shallow viscous flows are presented. The experiments, performed in a laboratory flume in both laminar and smooth turbulent flow conditions, complement the data already available in literature, and confirm that the hyperbolic trend shown by the Shields curve when the grain Reynolds number X decreases to zero is not supported by experimental evidence. In addition, they confirm the Yalin and Karahan (1979) hypothesis on the existence of a distinct curve for the inception of sediment transport in viscous dominated flows. On the basis of the observed phenomenology, we propose to interpret the process as a function of the probability distribution of the repose angle of the grains of the erodible bed. Accordingly, a simple mechanical relation is derived that explains the pattern exhibited by the experimental data.

DOI: https://doi.org/10.1080/00221680109499812

Year: 2001