Figure 3-39-A

Liquid stalling at entrance to round chamber.

The contact angle on all surfaces is 56 degrees, so Concus-Finn filaments do not form form. When the liquid tips reach the entrance to the bulge, there is a brief pause at the sharp corner until the floor contact line makes it just into the bulge, so the filament tip can make it around the corner. But the filaments cannot continue much beyond the corner.