A Co‐Spectral Budget Model Links Turbulent Eddies to Suspended Sediment Concentration in Channel Flows. Issue 3 (10th March 2022)

• Record Type: Journal Article
• Authors: Li, Shuolin; Bragg, Andrew D.; Katul, Gabriel
• Is Part Of: Water resources research. Volume 58:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-10
• Subjects: 1813 -- 1828; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2021WR031045
• Languages: English
• ISSNs: 0043-1397

Abstract

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. Key Points: A suspended sediment concentration (SSC) equation for turbulent flows is proposed and tested The equation is derived from a co‐spectral budget that accounts for energy distribution in all eddy sizes The effects of Reynolds number and a scale‐dependent Schmidt number on SSC are explicitly described