Diffusiophoretic dispersion of a colloidal blob in 2D porous media

The transport of solute and colloid mixtures through porous media are fundamental processes in both natural and engineered environments. In such systems, the existence of solute gradients induces a drift in the colloids either up (salt-attracting) or down the gradient (salt-repelling)--a phenomenon known as diffusiophoresis. In this work, we study the dispersion of a mixed blob of colloids and salt released in a 2D porous medium using numerical simulations and experiments. We observe that solute gradients modify the early-time dispersion of the colloidal blob, leading to reduced dispersion in the salt-repelling case and enhanced dispersion in the salt-attracting case. We further study the role of flow velocity distribution and Peclet number (Pe) by controlling the flow rate and introducing disorder into the lattice.