Kinetic study of head-on collisions of unequal-sized compound droplets

In this study, the head-on collision process of compound droplets of unequal sizes in a liquid environment is investigated using the volume of fluid method. The investigation reveals four main collision mechanisms: coalescence stabilization, coalescence release, rupture entrapment, and rupture coalescence. The transition between these collision mechanisms is analyzed in detail according to We. The effects of various initial collision parameters on the relative offset velocity CSrov, axial thicknesses l* and radial thicknesses h*, deformation coefficients, and core droplet release time Crt of compound droplet core shells were quantitatively analyzed. Additionally, this study examines the collision process of multi-layer compound droplets, revealing a more complex dynamic evolution of the interface, including the coalescence-release-entrapment phase and changes in the release direction. This study not only provides theoretical support for understanding the stability of compound droplets but also provides new insight into understanding multi-phase interactions in complex fluid systems.