A Co-Spectral Budget Model Links Turbulent Eddies to Suspended Sediment Concentration in Channel Flows

TitleA Co-Spectral Budget Model Links Turbulent Eddies to Suspended Sediment Concentration in Channel Flows
Publication TypeJournal Article
Year of Publication2022
AuthorsS Li, AD Bragg, and G Katul
JournalWater Resources Research
Volume58
Issue3
Date Published03/2022
Abstract

The vertical distribution of suspended sediment concentration remains a subject of active research given its relevance to a plethora of problems in hydraulics, hydrology, ecology, and water quality control. Many of the classical theories developed over the course of 90 years represent the effects of turbulence on suspended sediments (SS) using an effective mixing length or eddy diffusivity without explicitly accounting for the energetics of turbulent eddies across scales. To address this gap, the turbulent flux of sediments is derived using a co-spectral budget (CSB) model that can be imminently used in SS and other fine particle transport models. The CSB closes the pressure-redistribution effect using a spectral linear Rotta scheme modified to include isotropization of production and interactions between turbulent eddies and sediment grains through a modified scale-dependent de-correlation time. The result is a formulation similar in complexity to the widely used Rouse's equation but with all characteristic scales, Reynolds number, and Schmidt number effects derived from well-established spectral shapes of the vertical velocity and accepted constants from turbulence models. Finally, the proposed CSB model can recover Prandtl's and Rouse's equations under restricted conditions.

DOI10.1029/2021WR031045
Short TitleWater Resources Research