Forced capillary wetting of viscoelastic fluids
Xiong Wang1, Yijun Zeng2, Zhenyue Yuan2
1Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Centre for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong, China.
Journal of Colloid and Interface Science
|February 17, 2024
Summary
Forced wetting rapidly advances non-Newtonian fluid capillary filling, outperforming passive methods. Viscoelastic fluid dynamics, influenced by viscosity and capillary size, dictate wetting behavior, crucial for microfluidics and drug delivery.
Area of Science:
- Fluid dynamics
- Rheology
- Surface science
Background:
- Rapid capillary wetting is essential in natural and industrial processes.
- Passive wetting strategies are limited for high-viscosity and non-Newtonian fluids due to viscous resistance.
- Forced wetting offers a promising alternative for efficient non-Newtonian fluid capillary filling.
Purpose of the Study:
- To investigate the forced wetting behavior of viscoelastic fluids in capillaries.
- To understand the scaling relationships governing dynamic contact angles in forced wetting scenarios.
- To explore the influence of fluid properties and capillary dimensions on wetting dynamics.
Main Methods:
- Utilized Xanthan Gum (XG) aqueous solutions, a viscoelastic fluid, with storage modulus exceeding loss modulus.
- Employed smooth glass capillaries connected to a syringe pump for controlled high-speed fluid movement (up to 1 m/s).
Main Results:
- Identified a distinct power-law exponent for viscoelastic fluids compared to Newtonian fluids, characterizing the dynamic contact angle-velocity relationship.
- Observed that this exponent varies with viscoelastic fluid concentration and capillary diameter.
- Demonstrated that viscosity significantly influences wetting dynamics, with contact line morphology playing a key role.
Conclusions:
- Forced wetting is effective for rapid capillary filling with viscoelastic fluids.
- The wetting behavior of viscoelastic fluids is governed by a unique power-law scaling and is sensitive to fluid concentration and capillary geometry.
- Findings have significant implications for optimizing microfluidic devices and improving drug injectability.
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