In this paper, we develop a new correlation for the clean-bed filter coefficient (λ0) for Brownian particles, for which diffusion is the main deposition mechanism. The correlation is based on numerical Lattice-Boltzmann (LB) simulations in random packings of spheres of uniform diameter. We use LB methods to solve the Navier-Stokes equation for flow and then the advection-diffusion equation for particle transport. We determine a correlation for an "equivalent" single-collector diffusion efficiency, ηD, so that we can compare our predictions to "true" single-collector correlations stemming from unit-cell modeling approaches. We compared our new correlation to experiments on the filtration of latex particles. For small particle diameters, 50 nm < dp < 300 nm, when gravity and interception are negligible, our correlation for ηD predicts measurements better than unit-cell correlations, which overestimate ηD. The good agreement suggests that the representation of three-dimensional transport pathways in porous media plays an important role when modeling transport and deposition of Brownian particles. To model larger particles, for which gravity and interception are important too, we build a correlation for the overall single-collector efficiency η0 by adding corresponding ηG and ηI terms from unit-cell correlations to our ηD model. The resulting correlation predicts experiments with latex particles of dp > 300 nm well.
ASJC Scopus subject areas
- Environmental Chemistry