Hydrodynamics in unbaffled liquid-solid stirred tanks with (Abedpour, Salehnia et al. 2018)free surface studied by DEM-VOF method

Abstract DEM-VOF simulations of particle suspension dynamics in unbaffled liquid-solid stirred tanks with(Abedpour, Salehnia et al. 2018)free surfacewere performed in conjunction with RSM turbulence model.The two-way coupling of particle and fluid was achieved by solving Gidaspow’sdrag force, non-drag force and source term in the momentum equation. The calculation of particle volume in the fluid was realized by the porous model. Particle-particle and particle-wall interactionswere also considered.A four-blade 45° pitched blade turbinewasused, and the sliding-grid has been adopted to simulate impeller rotating.DEM-VOF coupling method was validated by theories and experiments.The effects of tank geometries,impeller rotating speed, particle density, diameter and volume fractiononthe free surface vortex, flow patternsand particle suspension dynamics were investigated by DEM-VOF method for the first time. Results indicate thatthe particle-fluid interaction has important effects on the flow field and particle distribution.The modifications oftank geometries substantially influenceflow patterns and particle suspension behaviors. The profiled bottom could eliminate sharp flow diversions completely. It can give rise to off-bottom suspension of particles and an elimination of the surface vortex due to particle-fluid interaction for large solid holdup and large particle diameter. Furthermore, the base of theprofiled bottom tank was optimized. The reported research data has important guiding significance for the design of stirred tanks.