Paper Number
SF17 

Session
Surfactants, Foams, and Emulsions

Title
Effect of wetting on pinch-off dynamics of wormlike micellar fluid

Presentation Date and Time
October 22, 2019 (Tuesday) 10:40

Track / Room
Track 5 / Room 306A

Authors (Click on name to view author profile)

1. Wu, Shijian (Florida State University, Chemical and Biomedical Engineering)
2. Mohammadigoushki, Hadi (Florida State University, Chemical and Biomedical Engineering)

Author and Affiliation Lines (in printed abstract book)
Shijian Wu and Hadi Mohammadigoushki
Chemical and Biomedical Engineering, Florida State University, Tallahassee, FL 32310

Speaker / Presenter 
Mohammadigoushki, Hadi

Text of Abstract
We conduct experiments by gradually depositing non-Newtonian wormlike micellar fluids onto a big solid substrate via a vertical needle. We investigate the filament thinning dynamics of the non-Newtonian fluids in combination with wetting on the flat substrate. Our work considers two wormlike micellar solutions based on CPCl/NaSal and OTAB/NaOA over a broad range of surfactant and salt concentrations. Two distinct flow behavior is observed. In regime I, the wetting does not significantly affect the filament thinning dynamics of the micellar solutions as the extensional relaxation times and Trouton ratios remain unchanged. However, in regime II, the fluid wetting on solid substrate impacts the filament thinning dynamics significantly by lowering the extensional relaxation time and the Trouton ratio. Our analysis shows that spreading of the wormlike micelles are reasonably well captured by Tanner's law proposed for spreading of Newtonian fluids on solid substrates. We propose a scaling analysis based on a combination of the wetting forces and viscous dissipation that can successfully distinguish these two flow regimes from each other.