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

Underwater obstacles are identified as local hotspots of various particulate matters in streams. As the transport particles is dependent on surrounding flow, we expect that flow structures created vicinity provide a favorable condition for high particle concentration. We quantify behaviors at small to intermediate range Stokes number they move past two forming gap varying length, based three indices: ratio entering gap, time span between entry and exit particles, integral scale flow. performed laboratory experiments recirculating racetrack flume using quantitative imaging, image velocimetry obtain velocity fields, tracking track full trajectory particles. length increases, interaction inner outer flows which followed by an increase decrease scale. Noticeably, indices converged when reached critical value were fully developed indicates with (St = 0.1–0.5) related large-scale motions. Understanding these patterns allow us select specific zones sample monitor both organic (seeds, eggs, larvae endemic aquatic species), inorganic (sediment microplastics) better management environments.