Aero‐breakup of droplets: Recent progress and outlook

Abstract

Abstract Aero‐breakup of droplets is a classic academic topic in fluid mechanics that describes the process of droplets breaking into multiple smaller ones or fine mists in an air flow. An in‐depth understanding of the aero‐breakup of liquid droplets is essential for the applications of spraying, atomization, ink printing, liquid fuel combustion, and other natural phenomenon explorations and industrial technology developments. Extensive studies have been conducted on this topic from different perspectives for decades. This review systematically summarizes the recent progress of droplet aero‐breakup studies. Starting from a brief introduction of research history, the intrinsic correlation between breakup modes and the governing parameters is sketched. The theoretical works on droplet breakup are first described from the views of interface instability theory and internal flow theory. These theories jointly construct the theoretical framework of droplet aero‐breakup. Second, several newly discovered breakup modes are demonstrated. Third, the influences of specific fluid properties, including viscosity, non‐Newtonian rheology, metallic natures, and volatility, on the mechanisms of droplet breakup are presented. The scenarios of multi‐droplet and droplet cloud are then discussed, which are believed to prevail in industrial applications. Last, an outlook for future explorations of droplet aero‐breakup is presented by providing several possible research directions.