Figure 2-23: Filaments moving down a channel with an enlargement, filaments not merging

Channel with bulge and constriction.

The amin 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. But the constriction is too narrow for separate filaments, so the filaments merge. After merging, the bulk filling of the channel proceeds away from the constriction on either side, but is much slower than the filaments, so it doesn't get very far in this animation. The contact angle on all surfaces is 15 degrees, so Concus-Finn filaments can form.