Bouncing characteristics of Janus drop impact on curved surfaces

Abstract

Manipulations of “complex” drops and their interactions with “complex” surfaces have attracted much attention in recent years. Here, we hypothesize that Janus drop impact on curved superhydrophobic surfaces can be highly affected by the curvature, Weber number (We), and viscosity difference between Janus components. The main objective is to predict the splitting of the low-viscosity component from the Janus drop. The study forms regime maps for the transition of non-splitting/splitting as a function of the parameters. It is shown that the We threshold, above which splitting occurs, can be tuned by altering the surface curvature and viscosity difference between low- and high-viscosity components. Asymmetric behavior observed in the two components is elucidated by establishing the relationship of the residence time and characterizing the dynamics by means of the horizontal momenta. The underlying mechanism for bouncing on asymmetric structures can provide a meaningful guidance on the designs of liquid purification or multi-material printing.