Effect of dead-end pores on anomalous transport in porous media

Heterogeneity in porous media may occur due to non-uniformity in the sizes or the shapes of grains that comprise the medium. We investigate the transport of colloids in a heterogeneous porous medium engineered in microuidic channels and featuring complex grain structures. Using experiment and numerical simulation, we investigate the velocity fields and the breakthrough curves of colloidal transport in a model porous medium by emphasising on the effects of dead-end pores. We characterize the porous structure via image processing and isolate dead-end sites from the remaining pore spaces. The study reveals complex flow structures inside dead-end sites that contribute to the small-scale velocity and long tails in the breakthrough curve. We provide a statistical model to capture the complex dynamics of the breakthrough curve.