Aerosols, Emulsions, Suspensions and Foams!

We study complex fluids and multiphase flows. Complex fluids are fluidic mixtures featuring multiple phases and mesoscopic length scales and include aerosol suspensions, liquid-liquid emulsions, film forming foams, polymeric solutions, and colloidal suspensions. These interface-rich systems are all around us in our everyday lives. Using macro- and micro-scale flow measurements and analytic mathematical modeling, we study such areas as the chemical microphysics of atmospheric aerosols, fluid dynamics and rheology of polymeric solutions, and interfacial phenomena of emulsions and foams. Currently, our active project areas explore:

  1. Dynamic surface tension and phase change of atmospheric aerosol particles.
  2. Surfactant transport and interfacial tension of oil-in-water and water-in-fuel emulsions.
  3. Dynamic interfacial tension and phase change of agricultural sprays. 
  4. Extensional rheology of fibril-forming polymer solutions.
  5. Sorting and encapsulation of pancreatic islets, all using advanced microfluidic platforms.
  6. Polymer-particle-flow interactions.
  7. Oil-in-water emulsion formation in a custom built Taylor-Couette geometry.

Schematic of trapped droplets in microfluidic wells (side view, and enlarged top view) for observing phase transitions of aerosol droplets and sprays. From Nandy et al. ACS Earth and Space Chemistry 2019. 

Narayan et al Langmuir 2020

Example of droplet coalescence event and measured film drainage times (2.7 seconds) in a 4 channel microfluidic trap. From Narayan et al. Langmuir 2020



Examples of complex series of transitions, including liquid-liquid phase separation (LLPS), observed in aqueous salt-organic mixture. Scale bar: 50 μm. From Nandy et al. ACS Earth and Space Chemistry 2019.