Profiles of the velocity (normal component V_x) along the interface between the two media (x = W_f) at different times. The velocity is negative when directed from the coarse medium to the fine one. The inset shows the filtration velocity distribution and pressure field (lines of various colors) at two different times (t = 50.3 h on the left, t = 80 h on the right) during the drying process. Fine column on the left, coarse column on the right.