Pore-scale simulation of the influence of grain material of artificial porous media on the motion and deposition of suspended particle

In this study, we investigated the effect mechanism of the grain material of artificial porous media coating quartz sand (SiO2), titanium dioxide (n-TiO2), zinc oxide (ZnO) and polystyrene (PS) on the motion and deposition of suspended particles. First, the relationship was deeply analysed between the DLVO potential energy and the physico-chemical properties of grain material, including the Hamaker constant and surface zeta potential. Second, the lattice Boltzmann method-immersed moving boundary-discrete element method (LBM-IMB-DEM) was used to investigate the motion characteristics of suspended particles and their effects, including the penetration rate, deposition rate, porosity reduction and the porosity-permeability relations. Third, the relations were innovatively explained between the energy barrier and the particles bridging and bridge collapse which cause the fluctuation of permeability reduction. The main results are as follows. (1) The descending order of the energy barrier between suspended particle and grain material is SiO2, ZnO, PS and n-TiO2, which is the same as that of the surface zeta potential of grain material. (2) For the suspended particles with the same size, the higher potential energy and Primary energy minimum (PEM) enhance the penetration rate. The particle deposition rate in porous media coating n-TiO2 is higher than others. (3) The highest non-uniformity of the porosity reduction occurs in the porous media coating the material with the lowest energy barrier. (4) For the grain material with lower energy barrier, the fluctuation frequency of permeability reduction is lower owing to the longer bridging time.