Sand Transport with Cohesive Admixtures…—Laboratory Tests and Modeling

Abstract

The paper presents results of experimental and theoretical studies on transport of water-sand mixtures in steady flow with small amounts of cohesive fractions. The experiments were carried out for sand alone and with cohesive admixtures in the form of clay in the amount of 5, 10, 15 and 20% by weight. The amount of sand fractions retained in the trap and along the control area was measured. The experimental results were compared with the calculation results for transport rate of sand fractions. An intended model of the vertical structure of both sand velocity and concentration as well as vertical mixing and sorting is proposed here in order to determine the influence of cohesive admixtures on the transport of sand fractions. Hence the reduction of sand fractions transport due to cohesion forces is included. The agreement of sand transport calculations according to the extended model with measured results and experimental data from literature was achieved within plus/minus a factor of 2.

Modelling of Granular Sediment Transport in Steady Flow Over a Mobile Sloped Bed

“…Solving the equations inside the contact layer (and upward) for each 𝑖 −th fraction leads to finding both the velocity 𝑢 (𝑧 ), as well as the concentration 𝑐 (𝑧 ). In this case, the axis 𝑧′′ is directed upward (Figure 2) due to the fact that the method of solution in these layers has been discussed in detail in papers [24] for homogeneous sediments and [29] for granulometrically heterogeneous sediments, and more recently in papers [27,28] for non-cohesive granulometrically heterogeneous sediments with cohesive additives, then the reader is referred to the mentioned papers for details of the solution.…”