Séminaire Café (Interne)

Il s’agit d’un exposé assez court (20 min) et assez informel.
Prière aux conférenciers de ne jamais dépasser 30 min et de vérifier la compatibilité avec le projecteur AVANT le séminaire.
Les séminaires ont lieu les jeudis après la réunion du laboratoire à 13h30 dans la bibliothèque du labo sur le campus Jussieu, Barre Cassan, Bât A, 1er étage.

Pour suggérer un titre et envoyer un abstract, contacter Joachim Trosseille (joachim.trosseille [AT] espci.fr, tél. 01 80 96 33 46), ou Manon L’Estimé (manon.lestime [AT] espci.fr, tél. 01 40 79 51 07).

Prochains séminaires café
2 mai Gustavo Martins (Doctorant au PMMH)
Numerical study of transients in bedload transportation
Sediment transport is an important process for the formation of patterns in nature. The reference case of steady and homogeneous transport has been much studied, with calibrated transport laws for the different modes of transport. In comparison, transients, both in time and space, which are crucial for the development of instabilities leading to those patterns, have been overlooked and their characteristics are much less known. This is especially true in the case of bedload, for which time and length scales associated with these transients are too small to be easily measured in experiments. Here, we investigate bedload by means of numerical simulations where a discrete element method (DEM) for the grains is coupled to a continuum description of the water flow using finite difference method (FDM). We specifically address the temporal response of the transport in the transition between two close steady states.
9 mai Armand Barbot (Doctorant au PMMH)
16 mai Daniel Nagy (PostDoctorant au PMMH)
Numerical simulation of the rheology of frictional spherocylinders
The dissipation during granular flow is characterized by the so-called effective friction coefficient, which is defined as the ratio of shear stress and confining pressure. This is in contrast to fluid flows, where dissipation is described by the viscosity. In the case of granular flows, the effective friction originates from microscopic contacts between the particles. Describing the rheology, one needs to measure the effective friction as a function of the dimensionless shear rate (the inertial number), which can be interpreted as the ratio of the macroscopic timescale of the shear flow and the timescale of the microscopic rearrangements of the flowing particles. The rheology of spherical particles has been studied previously by several authors. In our work, we focus on elongated particles, which are ubiquitous in industry and agriculture. They show more complex rheological properties, since elongated particles are rotating in the shear flow and hinder each other’s movement. In our simulations, we quantified how this complex dynamics changes the rheological properties of the system. We also study the origin of a unique behavior, the appearance of a secondary flow in certain geometries.
23 mai Mengfei He (Doctorant à l’université de Chicago)
Characteristic interfacial structure behind a rapidly moving contact line
When a spatula is quickly inserted into a honey jar, its moving surface drags a thin layer of air into the honey. We discovered that such a simple process produces a remarkable structure in the air layer. This structure is ubiquitous, robust, and is suggestive of a new fluid-mechanical instability. I will show our measurements using new interferometric techniques and describe a new analytic understanding of the flows.
30 mai Pas de séminaire (Ascension) ()
6 juin David Wilgenbus ( Responsable du pôle "ressources" - Fondation La main à la pâte)
13 juin Journées du labo
20 juin ()
27 juin ()

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Informations Pratiques

Laboratoire : 01 40 79 45 22
Directeur : Damien Vandembroucq
Codirecteur : Philippe Petitjeans
Administratrice : Frédérique Auger (01 40 79 45 22)
Gestionnaire : Claudette Barez (01 40 79 58 53)
Courriel : dir (arobase) pmmh.espci.fr

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