Figure 2. Simulated displacement patterns at various flow rates (Ca) and wetting properties (θ), for three degrees of disorder, λ.

Increasing λ decreases the displacement efficiency, in a manner that depends on both Ca and θ: promoting trapping and capillary fingering (CF) at slow drainage (low Ca and θ), and viscous fingering (VF) at high rates (regardless of θ). Reducing λ enhances the effect of the underlying geometry (the ordered lattice), which, together with the stabilizing effect of wettability results in faceted (FA) and ordered dendritic (OD) patterns at low and high Ca, respectively. Pores filled with invading and defending fluid are marked in black and white, respectively (solid not shown). Sample size is L = 260a.