2018/01/20 by Tomer Duman, Ran Holtzman, Duman, Tomer +3
Agricultural and Biological Sciences · Environmental Science · Mathematics · Physics and Astronomy · #Classical mechanics #Diffusion #Dispersion (optics) #Drag #FOS: Physical sciences #Flow (mathematics) #Flow velocity #Fluid Dynamics (physics.flu-dyn) #Flux (metallurgy) #Geology #Geometry #Gravitation #Groundwater flow and contamination studies #Horizontal plane #Hydrology and Sediment Transport Processes #Materials science #Mathematics #Mechanics #Optics #Particle (ecology) #Physics #Settling #Soil erosion and sediment transport #Taylor dispersion #Thermodynamics #Wake #physics.flu-dyn
paper · pdf · doi:10.48550/arxiv.1801.06746
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2018/01/20 · arxiv created 2018/01/21 · arxiv updated 2018/01/23 · openalex created_date 2022/10/03 · openalex updated_date 2026/08/06
The transport of heavy particles in a medium that consists of fluid and solid\nphases such as stream gravel beds, cracked soils and wetlands is affected by\nprocesses such as attachment-detachment, gravity and drag, and by mixing\nprocesses that are induced by Taylor dispersion and mechanical dispersion. This\npaper addresses an additional dispersion mechanism which is induced by\ngravitational settling and is a result of the coupling between the modified\nparticle concentration (the change of particle number density due to settling)\nand the lateral velocity profiles at the subscale. Heavy particles that move in\nareas of low horizontal velocity (e.g., near solid surfaces and wake regions)\nsettle closer to the release source as compared to particles in high velocity\nregions. The macroscopic concentration field of such suspensions is influenced\nby the ratio between the settling velocity and the subscale distribution of the\nhorizontal velocities. The objective of the study is to isolate and quantify\nthis type of dispersion using controlled flow scenarios. We used a Taylor brush\ngeometry (an array of vertical grooves) to numerically solve the flow.\nParticles were released from a vertical plane, generating a constant flux. The\nsubscale Eulerian concentration was compiled from simulated trajectories and\nthen spatially averaged to generate macroscopic concentration fields. The\nresults show that this settling-induced dispersion is significant in regions\nnear the source and that it cannot be modeled using Fick's law type of\nformulations. A parametric investigation shows that the location of the highest\ndispersion flux is linearly proportional to both the groove spacing and depth.\nA proposed model that estimates this location is used to evaluate where\nsettling-induced dispersion should not be ignored.\n