Shin, Seung-HoKam, Hyeong RyeolKim, Chang-Hun2015-02-232015-02-2320101467-8659https://doi.org/10.1111/j.1467-8659.2009.01637.xBy modeling mass transfer phenomena, we simulate solids and liquids dissolving or changing to other substances. We also deal with the very small-scale phenomena that occur when a fluid spreads out at the interface of another fluid. We model the pressure at the interfaces between fluids with Darcy s Law and represent the viscous fingering phenomenon in which a fluid interface spreads out with a fractal-like shape. We use hybrid grid-based simulation and smoothed particle hydrodynamics (SPH) to simulate intermolecular diffusion and attraction using particles at a computable scale. We have produced animations showing fluids mixing and objects dissolving.10.1111/j.1467-8659.2009.01637.x675-683