English

Juillet 2018 à Marseille : 16th International Workshop on the Physics of Compressible Turbulent Mixing (IWPCTM)

Site web : http://www.iwpctm16.fr/
Evènement organisé par les membres de l’axe de Recherche ECOCI

 

English

Séminaire IUSTI – 2 oct. 2020 – 11h salle 250

Viscoplastic droplets

Mazi Jalaal – DAMTP, Cambridge, UK

Viscoplastic or yield stress materials can behave like solids or fluids. Such materials, if not sufficiently stressed, behave like an elastic solid, but once the stress exceeds a critical value (the yield stress), the material deforms like a viscous fluid (typically with a nonlinear viscosity). I will discuss the effect of the yield stress on spreading droplets. I use experiments, asymptotic solutions, and numerical simulations to explain the dynamics and final shape of the droplets. Later, I will show how one can externally control the shape of a droplet, using temperature. For that, I will first present the rheological properties of a thermo-responsive material that undergoes sol(Newtonian)-gel(yield stress) transition upon heating. Then, I show the final diameter of a thermo-responsive droplet can be controlled by simply changing the surface temperature. In the same part of the thesis, we introduce a novel experimental method based on optical coherence tomography to identify the solidified region inside a droplet. Eventually, I will briefly discuss the other applications of viscoplastic droplets.

English

Événement co-organisé par des membres des Axes de Recherches : Combustion, Risques et Génie Civil & Écoulements Compressibles, Ondes de Choc et Interfaces Site web : http://www.iphmt20.fr

NEW DATES (after postponement due to COVID 19 ): 27 June -2 July 2021 : Interfacial Phenomena and Heat- Mass- Transfer (IPHMT20)

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Séminaire IUSTI – 4 septembre 2020 – 11h salle 250

Titre à venir

Olivier Millet – LaSIE, La Rochelle

Résumé à venir

English

Séminaire exceptionnel IUSTI – 29 juin 2020 – 11h salle 250

Titre à venir

Dongwhi Choi – ?, Corée du Sud

Résumé à venir

English

M.Souzy, H.Lhuissier, Y.Méheust, T.Le Borgne and B.Metzger

Aix Marseille Université, CNRS, IUSTI, UMR 7343, 13453 Marseille, France

Geosciences Rennes, UMR 6118, Université de Rennes 1, CNRS, 35042 Rennes, France
(Received 29 July 2019; revised 13 December 2019; accepted 5 February 2020)

Using index-matching and particle tracking, we measure the three-dimensional velocity field in an isotropic porous medium composed of randomly packed solid spheres. This high resolution experimental dataset provides new insights into the dynamics of dispersion and stretching in porous media. Dynamic-range velocity measurements indicate that the distribution of the velocity magnitude, U, is flat at low velocity (p(U) ~ U^0). While such a distribution should lead to a persistent anomalous dispersion process for advected non-diffusive point-particles, we show that the dispersion of non-diffusive tracers nonetheless becomes Fickian beyond a time set by the smallest effective velocity of the tracers. We derive expressions for the onset time of the Fickian regime and the longitudinal and transverse dispersion coefficients as a function of the velocity field properties. The experimental velocity field is also used to study, by numerical advection, the stretching histories of fluid material lines. The mean and the variance of the line elongations are found to grow exponentially in time and the distribution of elongation is log-normal. These results confirm the chaotic nature of advection within three-dimensional porous media. By providing the laws of dispersion and stretching, the present study opens the way to a complete description of mixing in porous media

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Séminaire IUSTI – 26 juin 2020 – 11h salle 250

Titre à venir

Pierre-Thomas Brun – Princeton Univ, ÉU

Résumé à venir

English

Séminaire IUSTI – 29 mai 2020 – 11h salle 250

Titre à venir

Raphaël Clément – IBDM, AMU, Marseille

Résumé à venir

English

Séminaire IUSTI – 15 mai 2020 – 11h salle 250

Titre à venir

Martin Trulsson – Lund University, Sweden

Résumé à venir

English

first_annoncement_v3-Purdue_IG-2

English

Séminaire IUSTI – 3 avril 2020 – 11h salle 250

Viscoplastic droplets

Mazi Jalaal – DAMTP, Cambridge, UK

Viscoplastic or yield stress materials can behave like solids or fluids. Such materials, if not sufficiently stressed, behave like an elastic solid, but once the stress exceeds a critical value (the yield stress), the material deforms like a viscous fluid (typically with a nonlinear viscosity). I will discuss the effect of the yield stress on spreading droplets. I use experiments, asymptotic solutions, and numerical simulations to explain the dynamics and final shape of the droplets. Later, I will show how one can externally control the shape of a droplet, using temperature. For that, I will first present the rheological properties of a thermo-responsive material that undergoes sol(Newtonian)-gel(yield stress) transition upon heating. Then, I show the final diameter of a thermo-responsive droplet can be controlled by simply changing the surface temperature. In the same part of the thesis, we introduce a novel experimental method based on optical coherence tomography to identify the solidified region inside a droplet. Eventually, I will briefly discuss the other applications of viscoplastic droplets.

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