Towards the development of a macro-structured water-repellent surface

Drop-surface interaction is predominant in nature as well as in many industrial applications. Freezing rain is the frequent origin of ice accretion on surfaces. Superhydrophobic surfaces show potential for anti-icing applications as they exhibit complete drop rebounce. Nonetheless, drop shedding has to take place before freezing for effective functioning. Recently, introducing a macro-ridge to break the hydrodynamic symmetry, has been shown to reduce the residence time on the surface of a bouncing drop. However, for a practical application the surface must be decorated with a series of ridges so that most of the drops actually encounter the ridges and lift-off rapidly. Here we show that a parallel neighbor ridge can influence the dynamics of recoiling. Ridge spacing plays a key role on the performance of surface to reduce the residence time. This finding can be of great significance for the development of macro-ridged anti-icing surfaces.