Fig. 3.

Emptying line for a capillary of triangular cross-section inscribed in a circle of radius R in three different orientations as a function of the contact angle θ. The meniscus cross-section at different points of the emptying line (circles) is shown under each diagram (A–E). The existence of corners in the cross-section creates a gap in the emptying line, for which the capillary empties for any size R, similar to that of very eccentric elliptical capillaries of Fig. 2. However, unlike this latter case, the emptying line rises vertically from $R/a=0$ (dashed red lines) and, upon approaching this line from the filled region, no tongue is formed in the meniscus. The emptying line of a circular capillary of radius R is included for comparison (dotted line).