Shuffling gait motion of an aerodynamically driven wall-bound drop

The lateral adhesion force on a wall-bound drop, propagating along a smooth rigid substrate, is measured using the drop adhesion force instrument (DAFI) and compared with the aerodynamic force applied to the drop in a fully developed channel flow. The agreement is rather good for relatively large capillary numbers. For very small capillary numbers the values of the adhesion and aerodynamic forces differ significantly. This unexpected result is explained by the drop propagation process influenced by the complex three-dimensional oscillations of the drop shape, similar to a shuffling gait.