Transport of Sediment Mixtures in Steady Flow with an Extra Contribution of Their Finest Fractions: Laboratory Tests and Modeling

Abstract

This paper presents the results of experimental studies on the transport of water-sandy mixtures with the content of very fine non-cohesive fractions in steady flow. The flow and shear velocity measurements as well as the measurements of sediment amount in the trap and control area were conducted. A theoretical model of the vertical structure of both velocity and concentration of sediment non-cohesive fractions as well as vertical mixing and sorting is presented here for transport calculations. The interaction effects between fractions are included, especially the influence of fine fractions in the mixture on transport of coarser fractions. The model provides an agreement between measurements and calculations of transport rate and grain size distributions of poorly sorted mixtures within plus/minus a coefficient of two. Further, the present model is used for calculating the limited contribution of very fine fractions in sediment due to deficit of those fractions in the bed. Again, the compliance of the calculations of sediment transport according to measurements is achieved. The satisfactory agreement between the calculations of grain size distributions and measurements is also found.

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.…”

Two-dimensional-one-dimensional splitting scheme for numerical solution of problems of suspended matter transport in coastal systems

“…As urbanization increases, anthropogenic pressure on the ecosystem of coastal areas increases. Without taking into account its influence, it is impossible to objectively assess the state of waters and effectively implement a policy of rational environmental management [1][2][3].…”