Figure 2-27-A: Filaments moving down channel with enlargements, not merging

Channel with three bulges.

The narrow parts of the channel are narrow enough to support bulk liquid progress, but also wide enough that separate Concus-Finn filaments can form. The bulges are too wide for bulk progress, so the filaments separate there and do not re-combine beyond the bulge. The contact angle on all surfaces is 30 degrees, so Concus-Finn filaments can form.