Paper Number
GR3
Session
Gallery of Rheology Contest
Title
Schlieren imaging of transition to turbulence for submerged jets of dilute polymer solutions via elasto-inertial streaks
Presentation Date and Time
October 23, 2019 (Wednesday) 6:30
Track / Room
Gallery of Rheology / Main Lobby on 3rd floor
Authors
- Yamanidouzisorkhabi, Sami (Massachusetts Institute of Technology, Department of Mechanical Engineering)
- McKinley, Gareth H. (Massachusetts Institute of Technology, Department of Mechanical Engineering)
- Bischofberger, Irmgard (Massachusetts Institute of Technology, Mechanical Engineering)
Author and Affiliation Lines
Sami Yamanidouzisorkhabi, Gareth H. McKinley, and Irmgard Bischofberger
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
Speaker / Presenter
Yamanidouzisorkhabi, Sami
Text of Abstract
Dilute synthetic and biopolymer solutions have been shown to reduce turbulent drag in pipelines and around marine vehicles due to their viscoelasticity. The very low concentrations of polymer employed in drag reduction studies makes direct imaging of the mixing and turbulent flow structures an outstanding challenge and necessitates an experimental technique to track the evolution of material lines in the dilute polymer solution phase. In this poster, we use Schlieren imaging to visualize jets of dilute aqueous polymer solutions injected into quiescent water. The two phases, i.e., dilute polymer solution and water, have a very small density difference (<1%) making their detection with naked eyes impossible. However, this small density difference provides enough refractive index difference that is tractable with Schlieren imaging. Our visualization not only shows that the turbulence structure is fundamentally different for dilute polymer solutions, but it also reveals a new mode of transition to turbulence that we call it Elasto-Inertial Streaks (EIS). Unlike transition to turbulence for Newtonian fluids, where intermittent turbulent regions between laminar regions, i.e., turbulent puffs, are observed, here the intermittency is completely eliminated and transition to turbulence occurs through the growth and development of streaks of dilute polymer solution phase around the core of the jet.