Influence of initial of droplet group on self-propelled jumping

Self-propelled droplet jumping phenomenon during condensation on superhydrophobic surfaces (SHS) has various engineering applications such as heat transfer enhancement, anti-icing/frosting and self-cleaning. In this paper, the initial characteristics, such as equivalent radius, symmetry and concentration, as well as jumping characteristics, such as energy conversion efficiency, departure time of the droplet group are defined by theoretical analysis. Subsequently, the relationship between initial characteristics and jumping characteristic are discussed by numerical simulation. The initial characteristics of droplet group, such as equivalent radius, symmetry, degree of concentration, have great influence on reflux process. Furthermore, the energy conversion efficiency, departure time of jumping process would also be affected. The efficiency of energy conversion is influenced by the symmetry of the droplet group. The better the symmetry is, the easier forming the reflux is, and the higher the efficiency of energy conversion is. The self-propelled jumping process could be roughly divided into two stages: the development of the liquid bridge and the jumping departure, the time of which determines the departure time of the droplets. When the concentration is the same, the larger the equivalent radius is, the more time the first stage of the jumping process costs. Besides, the decrease of the jumping speed leads to the lag of departure time. When the equivalent radiuses of the droplet groups are the same, the departure time is determined by the jumping velocity and the concentration, and the droplets with better degree of consideration and higher jumping speed would depart earlier.