Dynamics of a compound droplet in a microchannel containing a long obstacle

Abstract

In this work, we numerically analyze the breakup process of a two-dimensional compound droplet as it moves through a microchannel and encounters an obstacle embedded in it. Initially, the droplet is circular and concentric, and positioned near the inlet of the main channel. Under the influence of the inflow, the droplet moves toward the head of the obstacle, which has a semicircular shape. At a certain moment, the droplet and the obstacle interact with each other. With this interaction, simple daughter droplets and compound daughter droplets can be generated from the original droplet due to changes in the obstacle size, the inner droplet size, and especially the variation in surface tension described by the Weber number. The results reveal that with larger Weber numbers and smaller radii of the inner droplet and the obstacle, the compound droplet is completely separated. Based on the influence of these parameters, a phase diagram for the problem is constructed.