The Wet-Dog Shake

摘要

The drying of wet fur is a critical to mammalian heat regulation. In thisfluid dynamics video, we show a sequence of films demonstrating how hirsuteanimals to rapidly oscillate their bodies to shed water droplets, nature'sanalogy to the spin cycle of a washing machine. High-speed videography andfur-particle tracking is employed to determine the angular position of theanimal's shoulder skin as a function of time. X-ray cinematography is used totrack the motion of the skeleton. We determine conditions for drop ejection byconsidering the balance of surface tension and centripetal forces on dropsadhering to the animal. Particular attention is paid to rationalizing therelationship between animal size and oscillation frequency required toself-dry.