Turbulent Coherent Flow Structures to Predict the Behavior of Particles With Low to Intermediate Stokes Number Between Submerged Obstacles in Streams

Abstract

Transport of particles in rivers is a fundamental process in aquatic ecosystems relevant to various engineering and scientific problems, such as the removal of polluted particles, transport of organisms, optimal sampling of organic matter and sediment transport (McQueen et al., 2021;Prada et al., 2021;Shi et al., 2021). Since Elghobashi (1994) first defined the order of interaction between particle and turbulence based on volume fraction and time scales, flow physics became a significant aspect to understand the transport mechanism of particulate matter. For instance, microplastic pollution, which causes detrimental effect on aquatic biota and requires effective management strategies, can also be analyzed based on the close relation between flow and particulate matter (McCormick et al., 2014). Common obstacles in freshwater such as branches, logs, and hydraulic structures, are identified as local hotspots of particles as the obstacles create flow structures and influence their retention in water (Carmen et al., 2021;Kapp & Yeatman, 2018;Prada et al., 2020). Similarly, laboratory studies have been carried out to quantitively measure the transport and retention of drifting particles and devise effective removal techniques (Boos et al., 2021;Miehls et al., 2020;Palmer et al., 2004).Despite the wide application and numerous studies on particle transport, the knowledge about their interactions with aquatic ecosystems is still lacking due to the difficulties of analyzing continuous flow and discrete particles simultaneously. Immersed obstacles such as vegetation, bedforms, and hydraulic structures, complicate the analysis by introducing specific ranges of flow structures which affect transport of particles (Chung et al., 2021;Le Ribault et al., 2021;Soleimani & Ketabdari, 2020). Laboratory and numerical studies often simplify the complicated geometry and arrangement of such obstructions to understand how submerged obstacles disturb the flow, and questions remain on how to thoroughly account for the effects of transport mechanism of particles (Follett et al., 2021;Park & Hwang, 2019). Such simplifications include assumptions that replicate either cavity flow or porous flow media.Cavity flow is a classical problem that investigates how flow structures evolve in the presence of submerged obstacles with a simplified geometry. Depending on the aspect ratio of the cavity, the flow is categorized into: (a) closed cavity flow with a shear layer reattached to the bottom, (b) open cavity flow with the cutout bridged

Numerical Simulation of 3D Flow Structure and Turbulence Characteristics near Permeable Spur Dike in Channels with Varying Sinuosities

“…In their study, they measured flow velocities on multiple closely spaced parallel planes and reconstructed the pressure field to derive a water surface profile. Using PIV technology, You and Tinoco [32] conducted an indoor experiment in a circulating water flume to track the behavior of Stokes particles near underwater obstacles. They found that the flow structure formed near the barrier would provide favorable conditions for the migration of high concentrations of particulate matter.…”