Figure 2-20: Filaments moving down a channel with an enlargement, filaments not merging

Channel with bulge.

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 bulge is 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 15 degrees, so Concus-Finn filaments can form.