Effect of obstruction on the dynamics of compound droplets in microchannels

Abstract

This paper examines deformation and transport behavior of compound droplets when transported through microchannels with different geometries, including sinusoidal, sawtooth, diffuser, nozzle obstructions. The effect of capillary number (varying between 0.025 and 1) and obstruction size (0.4 Ro -0.8 Ro) on transition behaviour of compound droplets is studied systematically. The results indicate that capillary number is significant factor in deformation and stability of droplets. One of the values tested gave reliable outcomes with capillary number of 0.1 and even more accurate with 0.025. This implies that lower capillary numbers result in more accurate simulations, as they are precise in capturing interface dynamics and droplet-obstruction interactions. Transit time of outer and inner droplets decreases with obstruction ratio of 0.4–0.8, which means that obstructions of higher size facilitate faster droplet passage. This suggests that a lower capillary number enhances the precision of simulations by better capturing interface dynamics and droplet–obstruction interactions. The transit time for both outer and inner droplets decreases with increasing obstruction ratio from 0.4 to 0.8, indicating that larger obstructions facilitate faster droplet passage.