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Can hydrodynamic contact line paradox be solved by evaporation-condensation?
V Janeček1, F Doumenc2, B Guerrier1
1University Paris-Sud, CNRS, Lab FAST, Bat 502, Campus Universitaire, Orsay 91405, France.
Journal of Colloid and Interface Science
|September 9, 2015
Summary
Evaporation and condensation can regularize hydrodynamic contact line singularities in partial wetting systems. This phase change phenomenon, driven by vapor diffusion and Kelvin effect, conserves liquid mass but results in tiny characteristic length scales.
Area of Science:
- Fluid Dynamics
- Surface Science
- Thermodynamics
Background:
- Hydrodynamic contact line singularities pose challenges in fluid dynamics.
- Partial wetting configurations, like liquid wedges on substrates, are common in various applications.
- Evaporation-condensation dynamics are crucial in multiphase systems.
Purpose of the Study:
- To investigate the regularization of hydrodynamic contact line singularities using evaporation-condensation.
- To analyze the role of inert gas presence and isothermal conditions.
- To understand the interplay between mass exchange and meniscus curvature.
Main Methods:
- Multi-scale analysis incorporating lubrication equations for liquid dynamics.
- Modeling of vapor diffusion in inert gas and interfacial kinetic resistance.
- Inclusion of the Kelvin effect for coupling meniscus curvature and mass exchange.
Main Results:
- Phase exchange (evaporation and condensation) mathematically relieves the contact line singularity.
- Liquid mass is conserved due to exact compensation between evaporation and condensation.
- Numerical estimations for ethanol, water, and glycerol reveal extremely small characteristic length scales.
Conclusions:
- Evaporation-condensation offers a viable mechanism to regularize contact line singularities in partial wetting.
- The phenomenon is mathematically sound, conserving mass, but practically limited by minuscule length scales.
- Further research may explore applications where such small scales are relevant or can be manipulated.
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