
41Hydrodynamics of Pneumatic Foam
FIGURE 3.1
Demonstration of the capillary effect in a dry foam drawing liquid against the direction of
gravity.
r
FIGURE 3.2
A node of foam structure (left) where four Plateau borders meet. A single Plateau border
(right) of length L and the cross-sectional shape of a convex tricuspid of radius of curvature r.
(Courtesy of Stephan Koehler.)
FIGURE 3.3
A photograph of pneumatic foam of liquid fraction of approximately 4% taken through a pla-
nar transparent column wall.