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Inelastic non-Newtonian flow over heterogeneously slippery surfaces
A Sander Haase1, Jeffery A Wood1, Lisette M J Sprakel1
1Soft matter, Fluidics and Interfaces, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Physical Review. E
|March 17, 2017
Summary
This study shows how non-Newtonian fluid flow over slippery surfaces enhances wall slip. Shear-thinning fluids, like xanthan gum solutions, can achieve significantly increased slip lengths compared to Newtonian liquids.
Area of Science:
- Fluid Dynamics
- Materials Science
Background:
- Investigating fluid flow over complex surfaces is crucial for various engineering applications.
- Superhydrophobic surfaces with heterogeneous slip properties present unique challenges and opportunities for fluid control.
Purpose of the Study:
- To investigate inelastic non-Newtonian fluid flow over heterogeneously slippery surfaces.
- To quantify the enhancement of wall slip for shear-thinning fluids.
Main Methods:
- Numerical simulation of aqueous xanthan gum solutions over a bubble mattress (superhydrophobic surface).
- Theoretical analysis to derive an expression for maximum slip length.
Main Results:
- Wall slip can be significantly increased for shear-thinning fluids in the shear-thinning regime.
- A 3.2x enhancement in wall slip was observed for a 0.2 wt% xanthan gum solution compared to a Newtonian liquid.
- A theoretical model accurately predicted the slip enhancement.
Conclusions:
- Heterogeneously slippery surfaces can dramatically enhance wall slip for non-Newtonian fluids.
- The findings are applicable to systems where slip length is proportional to surface feature size.
- Maximum wall slip is achieved when fluid flow fully adapts to surface conditions.
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