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Convective Instability Driven by Diffusiophoresis of Colloids in Binary Liquid Mixtures
Carmine Anzivino1, Klejdis Xhani1, Marina Carpineti1
1Department of Physics "A. Pontremoli", University of Milan, via Celoria 16, 20133 Milan, Italy.
The Journal of Physical Chemistry Letters
|August 27, 2024
Summary
Colloidal particles dispersed in a binary fluid mixture can trigger convective instability. This instability arises from diffusiophoresis, leading to density inversion and pattern formation in the suspension.
Area of Science:
- Fluid dynamics
- Colloid science
- Thermodynamics
Background:
- Binary fluid mixtures typically exhibit stable mechanical equilibrium when solute concentration decreases with height.
- Concentration gradients drive diffusive fluxes to reach thermodynamic equilibrium.
Purpose of the Study:
- To investigate the effect of dispersed colloidal particles on the mechanical equilibrium of a binary fluid mixture.
- To understand the mechanism behind the observed convective instability in such systems.
Main Methods:
- Experimental observation of a binary fluid mixture with uniformly dispersed colloidal particles.
- Numerical analysis to elucidate the microscopic origins of the instability.
Main Results:
- The presence of colloidal particles destabilizes the mechanical equilibrium of the fluid mixture.
- Transient convection patterns emerge in the colloidal suspension.
- Diffusiophoresis drives colloids upward, creating a density-unstable layer.
Conclusions:
- Colloidal particle migration due to concentration gradients can induce convective instability.
- The system seeks to minimize gravitational potential energy through convection.
- This study reveals a novel mechanism for inducing fluid convection.
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