Paper Number
PO13 

Session
Poster Session

Title
Coalescence of passively trapped droplets in a microfluidic device with and without confinement

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom 1-2-3-4

Authors (Click on name to view author profile)

1. Panigrahi, Chinmayee (University of Minnesota, Mechanical Engineering)
2. Dutcher, Cari (University of Minnesota, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Chinmayee Panigrahi and Cari Dutcher
Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455

Speaker / Presenter 
Panigrahi, Chinmayee

Keywords
experimental methods; confined flows; emulsions; microfluidics; surfactants

Text of Abstract
The dynamics of coalescence of droplets can enlighten fundamental physics of emulsion stability. For surfactant-stabilized emulsions, the presence of heterogeneity (solid surface, particles, bubbles etc.) can greatly change the time scales for coalescence. We investigate the coalescence of two droplets, one of which is in adherence to a solid surface. A microfluidic chip with droplet generator and a passive hydrodynamic trap is fabricated. The T-junction generates micron-sized water in oil droplets that travel downstream and are trapped by the hydrodynamic forces. The continuous generation of droplets ensures a series of coalescence occurs at the trap. This is captured using a high-speed camera and the images are analyzed to measure the film drainage time and incoming velocity. The concentration of surfactant and the degree of confinement is also varied, and coalescence is quantified as a function of non-dimensional film drainage time, surfactant concentration, and capillary number.