Engineering Mechanics

Proceedings Vol. 14 (2008)

ENGINEERING MECHANICS 2008

Copyright © 2008 Institute of Thermomechanics, Academy of Sciences of the Czech Republic, v.v.i., Prague

 

Kharlamov A., Chara Z., Vlasak P.
pages 120 - +10p., full text

The bed load transport usually occurs in three consecutive modes: rolling, saltation, and suspension. The start of rolling motion is investigated widely, and different models are constructed and calibrated using available experiments. There are available few experiments and models for threshold between rolling and saltation. Herein the threshold of saltation in turbulent flow was determined and presented in common variables introduced by Shields (1936). The additional dimensionless parameter characterizing the bed surface formation was introduced. For the condition of the threshold there was chosen the equality of the submerged gravitational force and the lift force on a bed particle. For the low-studied shear induced lift force there were used data on well studied Magnus force on a rotating ball moving translationally in calm water. The critical shear stress as function of bed particle Reynolds number was determined analytically and reported in graphical form for different values of the bed parameter. The obtained results agree with available experiments on saltation start.

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