Figure 1.

Schematic of porous domain (left) with length scales ${\tilde{L}}_y$, the scale of one periodic unit cell, and ${\tilde{L}}_x$, the macroscopic length scale. The box (right) shows a zoomed in view of one periodic unit cell of the fluid domain, Ω, the boundary of the porous structure $\mathrm{\partial }\mathfrak{B}$ and the two different fluids ϕ=0 and ϕ=1 with interface width $\tilde{\mathrm{\lambda }}$. (Online version in colour.)