Convective Instability Driven by Diffusiophoresis of Colloids in Binary Liquid Mixtures
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arXiv
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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866912006429212672 |
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| author | Anzivino, Carmine Xhani, Klejdis Carpineti, Marina Verrastro, Stefano Zaccone, Alessio Vailati, Alberto |
| author_facet | Anzivino, Carmine Xhani, Klejdis Carpineti, Marina Verrastro, Stefano Zaccone, Alessio Vailati, Alberto |
| contents | In a binary fluid mixture, the concentration gradient of a heavier molecular solute leads to a diffusive flux of solvent and solute to achieve thermodynamic equilibrium. If the solute concentration decreases with height, the system is always in a condition of stable mechanical equilibrium against gravity. We show experimentally that this mechanical equilibrium becomes unstable in case colloidal particles are dispersed uniformly within the mixture, and that the resulting colloidal suspension undergoes a transient convective instability with the onset of convection patterns. By means of a numerical analysis, we clarify the microscopic mechanism from which the observed destabilisation process originates. The solute concentration gradient drives an upward diffusiophoretic migration of colloids, in turn causing the development of a mechanically unstable layer within the sample, where the density of the suspension increases with height. Convective motions arise to minimize this localized rise in gravitational potential energy. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_16432 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Convective Instability Driven by Diffusiophoresis of Colloids in Binary Liquid Mixtures Anzivino, Carmine Xhani, Klejdis Carpineti, Marina Verrastro, Stefano Zaccone, Alessio Vailati, Alberto Soft Condensed Matter Statistical Mechanics Pattern Formation and Solitons Chemical Physics Fluid Dynamics In a binary fluid mixture, the concentration gradient of a heavier molecular solute leads to a diffusive flux of solvent and solute to achieve thermodynamic equilibrium. If the solute concentration decreases with height, the system is always in a condition of stable mechanical equilibrium against gravity. We show experimentally that this mechanical equilibrium becomes unstable in case colloidal particles are dispersed uniformly within the mixture, and that the resulting colloidal suspension undergoes a transient convective instability with the onset of convection patterns. By means of a numerical analysis, we clarify the microscopic mechanism from which the observed destabilisation process originates. The solute concentration gradient drives an upward diffusiophoretic migration of colloids, in turn causing the development of a mechanically unstable layer within the sample, where the density of the suspension increases with height. Convective motions arise to minimize this localized rise in gravitational potential energy. |
| title | Convective Instability Driven by Diffusiophoresis of Colloids in Binary Liquid Mixtures |
| topic | Soft Condensed Matter Statistical Mechanics Pattern Formation and Solitons Chemical Physics Fluid Dynamics |
| url | https://arxiv.org/abs/2408.16432 |