Dynamic wetting of shear thinning fluids

G. K. Seevaratnam, Y. Suo, E. Ramé, L. M. Walker, S. Garoff

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

The impact of non-Newtonian behavior on dynamic wetting is critical since many fluids exhibit such behavior somewhere in the high-shear environment inherent in the wedge flow near a moving contact line. This impact will be different for two broad categories of non-Newtonian behavior, shear thinning, and elasticity. In this paper, we discuss the steady-state wetting of a fluid, aqueous solutions of xanthan gum, dominated by shear thinning but with negligible elasticity. In the shear thinning fluid, viscous bending near the contact line is greatly reduced compared to a Newtonian fluid having the same zero-shear viscosity. Concomitant with this reduction in viscous bending, the effective dynamic contact angle has a much weaker dependence on capillary number, Ca, than is observed in, or predicted for, Newtonian fluids. A simple lubrication model using a constitutive relation with power-law shear thinning at high shear rates and a Newtonian plateau at low shear rates mimics the trends seen in our data and elucidates the origins of the reduced viscous bending.

Original languageEnglish (US)
Article number012103
JournalPhysics of Fluids
Volume19
Issue number1
DOIs
StatePublished - Jan 2007
Externally publishedYes

Bibliographical note

Funding Information:
The authors acknowledge the support of NASA Grant No. NNC04GA34G. Rheometric equipment at CMU was made possible through funding from the PPG Foundation and the National Science Foundation (Grant No. CTS-9711110).

Keywords

  • Capillarity
  • Lubrication
  • Non-Newtonian flow
  • Non-Newtonian fluids
  • Shear flow
  • Viscosity
  • Wetting

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