A lattice‐gas and lattice Boltzmann study of mixing at continuous fracture Junctions: Importance of boundary conditions

The lattice‐gas automata and lattice Boltzmann (BGK) methods were used to estimate the mixing of fluid streams at a continuous fracture junction, for Peclet number ( Pe ) from 0 to 1547. Agreement with experimental results is good, particularly at Pe ≤ 25. At low Pe , a large fracture length/width is needed to obtain accurate mixing ratios ( M r ). For a 90° intersection of two fractures with equal widths and flow rates, M r approaches 0.5 (complete mixing) at Pe ≈ 1. At the highest Pe studied, M r =0.022, in contrast with the streamline routing prediction M r =0.