Late stage kinetics for various wicking and spreading problems.

The kinetics of spreading of a liquid drop in a wedge or V-shaped groove, in a network of such grooves, and on a hydrophilic strip, is reexamined. The length of a droplet of volume Omega spreading in a wedge after a time t is predicted to scale as Omega(1/5) t(2/5), and the height profile is predicted to be a parabola in the distance along the wedge. If the droplet is spreading radially in a sparse network of V-shaped grooves on a surface, the radius is predicted to scale as Omega(1/6) t(1/3), provided the liquid is completely contained within the grooves. A number of other results are also obtained.