Paper Number
IN18 

Session
Flow-induced Instabilities and Non-Newtonian Fluids

Title
Torsional fracture of viscoelastic liquid bridges

Presentation Date and Time
October 13, 2021 (Wednesday) 2:20

Track / Room
Track 4 / Meeting Room C-D

Authors (Click on name to view author profile)

  1. van Berlo, Frank (Eindhoven University of Technology)
  2. Chan, San To (Okinawa Institute of Science and Technology Graduate Univers, Micro Bio Nanofluidics Unit)
  3. Faizi, Hammad A. (Northwestern University)
  4. Matsumoto, Atsushi (University of Fukui, Applied Chemistry and Biotechnology)
  5. Haward, Simon J. (Okinawa Institute of Science and Technology Graduate Univers, Micro Bio Nanofluidics Unit)
  6. Anderson, Patrick D. (Eindhoven University of Technology)
  7. Chen, Amy Q. (Okinawa Institute of Science and Technology Graduate Univers, Micro Bio Nanofluidics Unit)

Author and Affiliation Lines (in printed abstract book)
Frank van Berlo1, San To Chan2, Hammad A. Faizi3, Atsushi Matsumoto2, Simon J. Haward2, Patrick D. Anderson1 and Amy Q. Chen2
1Eindhoven University of Technology, Eindhoven, The Netherlands; 2Micro Bio Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate Univers, Okinawa 904-0495, Japan; 3Northwestern University, Evanston, IL 60208

Speaker / Presenter 
Faizi, Hammad A.

Keywords
experimental methods; theoretical methods; computational methods; applied rheology; flow-induced instabilities; interfacial mobility; non-Newtonian fluids

Text of Abstract
Short liquid bridges are stable under the action of surface tension. In applications like electronic packaging, food engineering, and additive manufacturing, this poses challenges to the clean and fast dispensing of viscoelastic fluids. Here, we investigate how viscoelastic liquid bridges can be destabilized by torsion. By combining high-speed imaging and numerical simulation, we show that concave surfaces of liquid bridges can localize shear, in turn localizing normal stresses and making the surface more concave. Such positive feedback creates an indent, which propagates toward the center and leads to breakup of the liquid bridge. The indent formation mechanism closely resembles edge fracture, an often undesired viscoelastic flow instability characterized by the sudden indentation of the fluid’s free surface when the fluid is subjected to shear. By applying torsion, even short, capillary stable liquid bridges can be broken in the order of 1 s. This may lead to the development of dispensing protocols that reduce substrate contamination by the satellite droplets and long capillary tails formed by capillary retraction, which is the current mainstream industrial method for destabilizing viscoelastic liquid bridges.