“…In the literature, there are extensive experimental, theoretical, and computational investigations of different properties of multiphase systems, which are directly related to the topology and property of fluid‐fluid interfaces and capillary forces acting on them. Of these studies, we can refer to calculation of effective viscosity in viscous fingering regime [ Koval , 1963; Sorbie et al , 1995], averaging the phase pressures [ Zhang et al , 2007; Nordbotten et al , 2007; Yang et al , 2009; Korteland et al , 2009], scaling of the fingering with dynamic properties of a system [ Tallakstad et al , 2009], crossover behavior from viscous fingering to compact flow or from capillary fingering to viscous fingering [e.g., Wilkinson , 1986; Fernández et al , 1991; Ferer et al , 1993], nonequilibrium relative permeability curves [e.g., Goode and Ramakrishnan , 1993; Tsakiroglou et al , 2003; Theodoropoulou et al , 2005], relaxation time in fluid distribution [e.g., Buyevich , 1995], etc. Many of these issues cannot be explained by classical Darcy's law for multiphase flow.…”