Fig. 18. Unsteady flow resulting from steady supply to an inclined fracture. (a) Desaturated zone behind a fingertip in the 15- by 30-cm cell at steady supply (Q = 0.025 cm³ min^–1) under dry initial conditions (cos = 0.50). (b) Enlargement of the boxed area focuses on a single fluid blob. (c) Dynamic behavior within the boxed area is explored by recording changes in saturation with time. White represents repeated drain and fill cycles (e.g., drip points), while black indicates no change.