Paper Number
IN29 

Session
Flow-induced Instabilities in Non-Newtonian Fluids

Title
Influence of geometric ordering on viscoelastic flow instabilities in 3D porous media

Presentation Date and Time
October 13, 2022 (Thursday) 10:55

Track / Room
Track 5 / Sheraton 2

Authors (Click on name to view author profile)

  1. Chen, Emily Y. (Princeton University)
  2. Browne, Christopher A. (Princeton University)
  3. Haward, Simon J. (Okinawa Institute of Science and Technology)
  4. Shen, Amy Q. (Okinawa Institute of Science and Technology)
  5. Datta, Sujit S. (Princeton University)

Author and Affiliation Lines (in printed abstract book)
Emily Y. Chen1, Christopher A. Browne1, Simon J. Haward2, Amy Q. Shen2 and Sujit S. Datta1
1Princeton University, Princeton, NJ; 2Okinawa Institute of Science and Technology, Okinawa, Japan

Speaker / Presenter 
Chen, Emily Y.

Keywords
flow-induced instabilities; microscopy; polymer solutions

Text of Abstract
Many environmental and energy applications involve the flow of viscoelastic polymer solutions in 3D porous media with complex geometries. As the polymers are transported through the tortuous pore space, elastic stresses build up, leading to the onset of chaotic spatiotemporal flow fluctuations as a threshold flow rate is exceeded. Our previous studies in disordered 3D media suggested that the onset of this instability is highly sensitive to the geometry of the medium; however, how exactly geometry influences the flow instability remains unclear. We address this gap in knowledge by directly imaging the flow in microfabricated 3D porous media with precisely controlled ordered geometries consisting of body-centered cuboid (BCC) or simple-cubic (SC) arrays of spheres. Unexpectedly, in both cases, we find that the flow instability is generated and localized upstream of the contact regions between spheres rather than at the sphere surfaces—suggesting that the consolidation of solid grains, which is inherent in naturally-occurring media, may play a pivotal role in establishing the flow instability in field settings. However, the characteristics of the flow instability are strongly dependent on the particular unit cell geometry: in BCC arrays, the instability manifests as continual ‘wobbles’ in the flow, whereas in SC arrays, it manifests through the formation of recirculating eddies. For each case, we further quantify how the features of this flow instability control the macroscopic resistance to flow through the entire medium. Altogether, our work provides a key step towards elucidating how porous medium geometry shapes viscoelastic flow behavior.