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Bénard instabilities in a binary-liquid layer evaporating into an inert gas
H Machrafi1, A Rednikov, P Colinet
1Université de Liège, Thermodynamique des Phénomènes Irréversibles, Institut de Physique B5a, Allée du 6 Août, 17, B-4000 Liège 1, Belgium. H.Machrafi@ulg.ac.be
Journal of Colloid and Interface Science
|June 19, 2010
Summary
The solutal Marangoni effect is the primary driver of instability in evaporating water-ethanol mixtures. This instability, crucial for understanding fluid dynamics, is largely unaffected by water evaporation.
Area of Science:
- Fluid Dynamics
- Chemical Engineering
- Thermodynamics
Background:
- Investigates instabilities in binary liquid layers with evaporation.
- Focuses on a water-ethanol system under specific boundary conditions.
Purpose of the Study:
- To perform a linear stability analysis of an evaporating binary liquid layer.
- To compare solutal and thermal Marangoni and Rayleigh effects.
- To determine critical parameters for instability onset.
Main Methods:
- Linear stability analysis of a horizontal binary liquid layer.
- Calculation of neutral stability curves using solutal/thermal Marangoni/Rayleigh numbers and wavenumber.
- Consideration of fixed ambient mass fraction and temperature, and fixed bottom conditions.
Main Results:
- The solutal Marangoni effect is identified as the dominant instability mechanism for a 10wt.% water-ethanol mixture.
- The global action of the solutal Marangoni effect can be modeled using a Pearson-like model with a wavenumber-dependent Biot number.
- Water evaporation has a minor quantitative impact on the predominant solutal Marangoni mechanism.
Conclusions:
- Solutal Marangoni convection is the key instability in this system.
- The system's behavior can be predicted with a simplified model.
- Water evaporation plays a secondary role in the overall instability dynamics.
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