Going down: a droplet of honey in a superhydrophobic coated tube. (Courtesy: Aalto University) Honey and other highly viscous fluids can flow faster than water in specially coated capillary tubes.

The hummingbird tongue is a fluid trap, not a capillary tube. Proceedings of the National Academy of Sciences. Vol. 108, June7, 2011, p. 9356. doi: 10.1073/pnas.1016944108.

A popular metering device used on many fractional horsepower refrigeration systems is the capillary tube. One field problem frequently encountered with this type of metering device is that it can ...

References [1] Tube radial distribution chromatography system developed by combining commercially available HPLC system and open-tubular capillary tube as separation column. Talanta (2018).