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Startseite > Séminaires > Archives séminaires > Séminaires 2021 > Visio-Séminaire MSC. 14 juin 2021. Jean Colombani (ILM, Lyon) : "Coffee-stain effect with pure water on a soluble substrate".

Visio-Séminaire MSC. 14 juin 2021. Jean Colombani (ILM, Lyon) : "Coffee-stain effect with pure water on a soluble substrate"

Sauf mention contraire, les séminaires et les soutenances se déroulent à 11h30 en salle 454A du bâtiment Condorcet.

There will be a live diffusion with Zoom.

Monday June 14th, 11h30.

Contact Michael Berhanu to attend the video seminar

Coffee-stain effect with pure water on a soluble substrate

Jean Colombani

Institut Lumière Matière ; Université de Lyon ; Université Claude Bernard Lyon 1 ; CNRS UMR 5306

When the sessile droplet of a complex fluid has evaporated, a ring-shaped deposit is left on the substrate (the coffee-stain effect). This effect is a consequence of an outward flow inside the droplet, which derives from the pinning of the triple line. We have recently shown that this effect can be observed when a pure water drop evaporates on a fast dissolving solid, like salt. In this configuration, the dissolved salt is advected toward the pinned contact line, where the increased evaporation induces the supersaturation of the salt, which leads to the salt crystallization as a thin film, following the interface. This thin shell at the periphery of the drying drop shows shapes varying from inclined walls to hollow half-tores. We have modeled analytically our experiments to understand how the open or closed shape is selected by the droplet radius and contact angle, and to predict the order of magnitude of the shell thickness. I will present the experimental device, the main results obtained on earth and in microgravity, the flow pattern inside the drop, the phase diagram of the shells and I will introduce briefly the analytical model.

Contact : Équipe séminaires / Seminar team - Published on / Publié le 26 mars 2020

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