The variation of flow and turbulence across the sediment-water interface

Abstract

A basic framework characterising the interaction between aquatic flows and permeable sediment beds is presented here. Through the permeability Reynolds number (ReK = Ku/ν, where K is the sediment permeability, uis the shear velocity and ν is the fluid viscosity), the framework unifies two classical flow typologies, namely impermeable boundary layer flows (Rek ≪1) and highly permeable canopy flows (Rek ≫ 1) . Within this range, the sediment-water interface (SWI) is identified as a transitional region, with Rek in aquatic systems typically O(0.001-10). As the sediments obstruct conventional measurement techniques, experimental observations of interfacial hydrodynamics remain extremely rare. Th..