A numerical investigation on the morphology evolution of compound droplets

The volume of fluid-continuum surface force model is used to systematically study the influence of characteristic parameters, internal pressure on the dynamic characteristics, finite deformation mode, and fracture mode of compound droplets in air. The simulation results indicate that the morphology evolution of compound droplets can be divided into two stages: expansion deformation stage and irregular deformation stage. And for the first time, it is proposed that the crushing methods of compound droplets can be divided into two types: overall oscillation and local oscillation. Increasing the internal pressure of the compound droplet will cause severe deformation of the compound droplet, and the time required for the expansion and deformation stage will be reduced. However, the influence of fluid interfacial tension and viscosity on the bottom dynamics of compound droplets is often complex, leading to significant changes in the deformation mode of compound droplets. In addition, the influence of feature parameters We and Ca is further discussed. The research results can provide theoretical guidance for precise control of their arrangement in core–shell driven microfluidic technology.