Study on particles sedimentation in porous media with the immersed boundary-lattice Boltzmann flux solver

Particles sedimentation in porous media is ubiquitous in natural and industrial fields. In this work, the immersed boundary method (IBM) and the lattice Boltzmann flux solver (LBFS) were combined to study the particles sedimentation in porous media for the first time. The hybrid method (IB-LBFS) preserves the advantages of the IBM in treating the solid-fluid boundaries and the LBFS in solving the fluid flow. The effects of porous media arrangement, particle-fluid density ratio, specific surface area, and particle diameter on the behaviors of the settling particles were discussed systematically. The results show that compared with the staggered array porous media, the in-line array porous media are beneficial for particles transport because of the low tortuosity. It is easier for the particles with high density to descend among obstacles due to a higher inertia. The averaged longitudinal coordinate of particles decreases rapidly for higher density ratio, whereas decreases slowly for lower density ratio. For porous media with identical porosity, the channel in porous media with large specific surface area is narrow, leading to the increase in gas-solid interaction and the decrease in particle flow velocity. In addition, for particles with the same total mass, the small particles are easier to descend than the large particles owing to the low collision probability between particles and porous media. The present work not only demonstrates the capacity of the IB-LBFS to deal with complicated fluid-solid interaction problems, but also sheds light on the mechanism of particles sedimentation in porous media.