Modelling suspended sediment in environmental turbulent fluids

TL;DR

This paper presents a new model for lateral sediment transport in turbulent environmental flows, derived from 3D turbulence models, capturing key physical effects and validated against experimental data and simulations.

Contribution

It introduces a systematic derivation of a sediment transport model from 3D turbulence equations using center manifold theory, including sediment-fluid interactions.

Findings

Vertical velocity and concentration distributions match experimental data.

Model predicts realistic sediment behavior under large wave conditions.

Includes effects of erosion, advection, and dispersion.

Abstract

Modelling sediment transport in environmental turbulent fluids is a challenge. This article develops a sound model of the lateral transport of suspended sediment in environmental fluid flows such as floods and tsunamis. The model is systematically derived from a 3D turbulence model based on the Smagorinski large eddy closure. Embedding the physical dynamics into a family of problems and analysing linear dynamics of the system, centre manifold theory indicates the existence of slow manifold parametrised by macroscale variables. Computer algebra then constructs the slow manifold in terms of fluid depth, depth-averaged lateral velocities, and suspended sediment concentration. The model includes the effects of sediment erosion, advection, dispersion, and also the interactions between the sediment and turbulent fluid flow. Vertical distributions of the velocity and concentration in steady flow agree with the established experimental data. Numerical simulations of the suspended sediment under large waves show that the developed model predicts physically reasonable phenomena.