Pore-scale study of the collector efficiency of nanoparticles in packings of nonspherical collectors

Pore-scale simulations of flow and transport through a filter were used to predict clean-bed filtration of nanoparticles from a 3D image of the filter. X-ray micro-computed tomography was used to obtain the geometry and topology of the filter consisting of flattened half-spherical collectors. A Lattice-Boltzmann method was used to model fluid flow and particle transport in the volumetric image of the filter. Nanoparticles are considered that are so small that diffusion, as compared to the processes of gravitational settlement and interception, dominates particle deposition. A correlation equation is determined for the average collector efficiency for diffusion through regression analysis performed for a set of numerical breakthrough experiments for a range of suspended particle sizes and Darcy velocities. This correlation quantifies the collector size by the surface average equivalent sphere diameter. The newly derived correlation agrees well with experimental data.