Estimating Extensional Flow Resistance in Viscoelastic Fluids

Strategic Insights -

Researchers from the University of Toronto have developed an experimental technique to estimate the extensional flow resistance of dilute polymer solutions using flow in a lubricated, converging, and microfluidic channel. The channel's two-dimensional hyperbolic profile and the introduction of a less viscous Newtonian fluid through side channels upstream create a unique setup for studying fluid behavior. The researchers observed differences in flow patterns between miscible and immiscible lubricants, achieving stable flows with an immiscible lubricant and suitable interfacial tension.

Key Takeaways:

  • The researchers developed an experimental technique to estimate the extensional flow resistance of dilute polymer solutions in a microfluidic channel with a two-dimensional hyperbolic profile.
  • The technique involves introducing a less viscous Newtonian fluid through side channels upstream to create a unique flow setup.
  • Differences in flow patterns were observed between miscible and immiscible lubricants, with stable flows achieved with an immiscible lubricant and suitable interfacial tension.
  • Steady extensional flows were established at low Reynolds numbers, consistent with literature values.
  • The values of the Trouton ratio for dilute solutions of high-molecular-weight polyethylene oxide were found to be around O(10^3), consistent with literature values.
  • The study highlights the importance of understanding fluid behavior in microfluidic devices, which is crucial for various applications, including nanotechnology and biomedical devices.

Statistics:

  • Reynolds numbers (Re) were established at low values, indicating a laminar flow regime.
  • The Trouton ratio values for dilute solutions of high-molecular-weight polyethylene oxide were found to be around O(10^3).
  • The study involved the use of a microfluidic channel with a two-dimensional hyperbolic profile.

Sources:

  • Wang, et al. "Lubricated Extensional Flow of Viscoelastic Fluids in a Convergent Microchannel." Journal of Rheology, vol. 55, no. 5, 2011, pp. 1103-1126.
  • University of Toronto, Department of Mechanical and Industrial Engineering.
  • Journal of Rheology, American Institute of Physics, Ste. 1, No. 1, 2 Huntington Quadrangle, Melville, NY 11747-4502, USA.