Figure 8-30-B

Liquid in square bundle of 16 non-uniform rods.

The contact angle on the inner rods is 30 degrees and 125 degrees on the outside rods. The gap between the rods is one rod radius. The forward pull of the center rods is not enough to drag the liquid forward on the outside rods. The liquid retreats on the outside rods, completely dewetting them, leaving the liquid to advance wetting only the inside rods. See this interactive app to explore liquid wicking in rods,