Modeling self-assembly and capture phenomenon of two droplets in high aspect ratio microchannels

Abstract

Abstract Droplets will self-organize into stable and periodic arrangements of crystalline morphology when moving in high aspect ratio microchannels. Theoretical analysis of the behaviors is necessary to find the assembly mechanism and for applications. Here, we do modeling study to the experimental phenomenon that two droplets with different sizes show dynamic self-assembly or capture behaviors in high aspect ratio microchannels. Three stages (disturbance, self-assembly and relative stability) are used to describe the droplets motion process and the Stokes solutions are obtained in tangent sphere coordinates. Comparisons of the forces verify the validity of the theoretical results and trajectory analysis shows the dynamic assembly or capture process of droplets. We find that an arbitrary small turbulence changes the forces acting on droplets, breaks the equilibrium, and finally, the two droplets form a stable arrangement and move together. The relative motion of droplets contributes to the assembly or capture process. This work offers theoretical explanation of the experimental results, and can be conducted for more droplets assembly studies and probable applications such as the synthesis of new particle materials and information expression.