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Pré-Publication, Document De Travail Année : 2015

Diffusiophoresis at the macro-scale

Résumé

Diffusiophoresis, a ubiquitous phenomenon which induces particle transport whenever solute gradients are present, was recently put forward in the context of microsystems and shown to strongly impact colloidal transport (from patterning to mixing) at such scales. In the present work, we show experimentally that this nanoscale-rooted mechanism can actually induce changes in the \textit{macro-scale mixing} of colloids by chaotic advection. Rather than the usual decay of standard deviation of concentration, which is a global parameter, we use different multi-scale tools available for chaotic flows or intermittent turbulent mixing, like concentration spectra, or second and fourth moments of probability density functions of scalar gradients. Not only those tools can be used in open flows (when the mean concentration is not constant), but also they allow for a scale by scale analysis. Strikingly, diffusiophoresis is shown to affect all scales, although more particularly the smallest one, resulting in a change of scalar intermittency and in an unusual scale bridging spanning more than 7 orders of magnitude. Quantifying the averaged impact of diffusiophoresis on the macro-scale mixing, we finally explain why the effects observed can be made consistent with the introduction of an effective P\'eclet number.
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Dates et versions

hal-01242358 , version 1 (15-12-2015)
hal-01242358 , version 2 (28-05-2016)
hal-01242358 , version 3 (06-07-2016)
hal-01242358 , version 4 (12-07-2017)

Identifiants

  • HAL Id : hal-01242358 , version 1

Citer

C. Mauger, R. Volk, N. Machicoane, M. Bourgoin, C. Cottin-Bizonne, et al.. Diffusiophoresis at the macro-scale. 2015. ⟨hal-01242358v1⟩
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