Droplet formation of yield stress fluids in asymmetric parallelized microchannels

Abstract

The microemulsion method is limited due to low productivity. Using Carbopol gel (0.05 %, 0.13 %, 0.2 %) and mineral oil as dispersed phase and continuous phase respectively (3 ≤ Qd ≤ 8, 2 ≤ Qc ≤ 350), the numbering-up of YSFs droplets in asymmetric parallel microchannels are experimentally studied. Ca*(10-3-10) and Cac (10-4-10-2) are introduced to divide the two-dual droplet flow pattern which is conducive to production. It is found that yield stress mainly acts on the necking stage of droplet formation, so the continuous phase flow can be increased to shorten the necking time and improve the size uniformity. The influence of rheology on droplet morphology makes the existing multiphase flow pressure drop model no longer applicable. Therefore, a correction pressure drop model of Carbopol slugs and prediction models of droplet size and generation frequency are proposed. This study provides a reference for the high-throughput production of YSFs droplets in microchannels.