Paper Number
PO38                         My Program 

Session
Poster Session

Title
Flow of wormlike micellar solutions over concavities

Presentation Date and Time
October 16, 2024 (Wednesday) 6:30

Track / Room
Poster Session / Waterloo 3 & 4

Authors (Click on name to view author profile)

  1. Hillebrand, Fabian (Okinawa Institute of Science and Technology)
  2. Varchanis, Stylianos (Flatiron Institute, Simons Foundation, Center for Computational Biology)
  3. Hopkins, Cameron C. (Okinawa Institute of Science and Technology)
  4. Haward, Simon J. (Okinawa Institute of Science and Technology Graduate Univers, Micro,Bio,Nanofluidics Unit)
  5. Shen, Amy Q. (Okinawa Institute of Science and Technology Graduate Univers, Micro,Bio,Nanofluidics Unit)

Author and Affiliation Lines (in printed abstract book)
Fabian Hillebrand1, Stylianos Varchanis2, Cameron C. Hopkins1, Simon J. Haward1 and Amy Q. Shen1
1Micro,Bio,Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate Univers, Onna-son, Okinawa 904-0495, Japan; 2Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, NY 10010

Speaker / Presenter 
Haward, Simon J.

Keywords
experimental methods; computational methods; non-Newtonian fluids; surfactants

Text of Abstract
We present a comprehensive investigation combining numerical simulations with experimental validation, focusing on the creeping flow behavior of a shear-banding, viscoelastic wormlike micellar (WLM) solution over concavities with various depths (D) and lengths (L), and over a range of Weissenberg numbers Wi. The fluid is modeled using the diffusive Giesekus model, with model parameters set to quantitatively describe the shear rheology of a 100:60 mM cetylpyridinium chloride:sodium salicylate aqueous WLM solution used for the experimental validation. We observe a transition from “cavity flow” to “expansion-contraction flow” as the length L exceeds the sum of depth D and channel width W. This transition is manifested by a change of vortical structures within the cavity. For L = D + W, “cavity flow” is characterized by large scale recirculations spanning the concavity length. For L > D + W, the recirculations observed in “expansion-contraction flow” are confined to the salient corners downstream of the expansion plane and upstream of the contraction plane. Using the numerical dataset, we construct phase diagrams in L-D at various fixed Wi, characterizing the transitions and describing the evolution of vortical structures influenced by viscoelastic effects.