Hydrodynamic Forces on Raised Particles Above the Top Layer of a Particulate Bed and Vortex induced Resuspension

Understanding the drag and lift forces acting on particles located at or above the top layer of a packed bed is critical for accurately modeling sediment transport and particle resuspension in environmental and industrial flows. Traditional models often rely on force correlations developed for particles surrounded by homogeneously distributed neighbors or for particles near smooth walls, neglecting the asymmetric flow conditions experienced by particles located at top of the bed. In this study, we employ the lattice Boltzmann method (LBM) to resolve the flow around individual particles situated in and above structured porous beds. Our simulations systematically examine the influence of bed configuration and neighboring partices on hydrodynamic forces, revealing the limitations of existing drag and lift models in predicting forces in these asymmetric environments. Additionally, we analyze how drag and lift evolve as particles roll over their neighbors, capturing force variations with angular displacement. The results provide new insights into the anisotropic shielding effects at the bed interface and offer accurate force data essential for improving predictive models of resuspension and bedload transport in complex flows. To further explore resuspension mechanisms, we extend the analysis to vortex-particle interactions by considering isolated vortices. By simulating isolated vortices interacting with packed beds using a coupled lattice Boltzmann method and discrete element method (LBM-DEM), we isolate the effects of coherent flow structures on particle entrainment.