Paper Number
FI22 My Program
Session
Flow-Induced Instabilities and Non-Newtonian Fluids
Title
Drawing parallels: Small-scale canopy elastic turbulence versus large-scale inertial turbulence
Presentation Date and Time
October 15, 2024 (Tuesday) 11:10
Track / Room
Track 5 / Room 405
Authors
- Lopez de la Cruz, Ricardo A. (Okinawa Institute of Science and Technology Graduate Univers)
- Haward, Simon J. (Okinawa Institute of Science and Technology Graduate Univers, Micro,Bio,Nanofluidics Unit)
- Shen, Amy Q. (Okinawa Institute of Science and Technology Graduate Univers, Micro,Bio,Nanofluidics Unit)
Author and Affiliation Lines
Ricardo A. Lopez de la Cruz, Simon J. Haward and Amy Q. Shen
Micro,Bio,Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate Univers, Onna-son, Okinawa 904-0495, Japan
Speaker / Presenter
Lopez de la Cruz, Ricardo A.
Keywords
flow-induced instabilities; non-Newtonian fluids; polymer solutions
Text of Abstract
Since its discovery nearly two decades ago, elastic turbulence (ET) has been extensively investigated across various systems with diverse geometries, spanning curved and straight channels, as well as porous media. Recognized for its parallels with inertial turbulence and its potential applications in microfluidics, ET has garnered significant interest in elucidating the conditions triggering it, its flow dynamics, and its interplay with inertial turbulence. While progress has been notable in curved geometries, questions persist regarding straight channels and more intricate systems. Here, we investigate the latter scenario, specifically exploring a canopy within a microfluidic device, drawing upon insights gleaned from simpler flows. Our investigation begins with examining the flow characteristics of a viscoelastic fluid at varying Weissenberg numbers, revealing distinct flow regimes dictated by the rheological properties of the fluid and flow conditions. Focusing on the ET regime, we study the mean and fluctuating velocity fields, observing a delineation of the flow into distinct regions reminiscent of porous media within the canopy, a mixing-layer-like flow at the canopy tips, channel flow away from the canopy, and a transitional zone between the mixing layer and channel flow in the presence of ET. Local fitting of the average flow profiles with models corresponding to specific flow types—Brinkman equation, hyperbolic tangent, and Poiseuille profile—illustrates the flow dynamics at each location. Lastly, we assess the robustness of these models under variations in canopy geometry and fluid rheology. Our findings demonstrate that the complex ET flow in such systems can be effectively characterized by leveraging simpler analogues and drawing insights from conventional turbulence, thereby enhancing our understanding of real-world scenarios like cilia in bacteria or within mammalian bodies.