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PMMH’s weekly seminar is held every Friday at 11 am (map)
Laurent Duchemin
Sylvain Patinet
Stéphane Perrard
Etienne Reyssat
Virgile Thiévenaz
PMMH
BARRE CASSAN
BAT A 1ER ETAGE CASE 18
7 QUAI SAINT BERNARD
75005 PARIS
France
Tel : (33) 1 40 79 45 22
Séminaire PMMH - Benjamin Guiselin - ENS Lyon
Emergence of spontaneous collective oscillations in dense Human crowds
Massive crowd gatherings form some of the most dangerous and unpredictable environments [1]. However, we lack quantitative characterizations of their dynamics and the heuristic principles used to explain and predict their motion remain elusive. In this talk, I will present our analysis of the dynamics of thousands of packed individuals in a model system, namely, the opening ceremony of the festival of San Fermín in Pamplona, Spain [2]. This analysis reveals that at extreme densities crowds experience self-sustained oscillatory flows, which echo the correlated orbital motion of hundreds of individuals in the absence of any external guidance. I will then detail how the combination of mechanics and symmetry principles has allowed us to establish a robust predictive model of dense crowds inferred from our measurements to elucidate this emergent chiral dynamics. In particular, we establish that the self-organization of crowds into macroscopic oscillators originates from transverse frictional forces between the crowd and the ground.
[1] D. Helbing, A. Johansson, and H. Z. Al-Abideen. ``Dynamics of crowd disasters : An empirical study''. Physical Review E, 75(4), 046109 (2007).
[2] F. Gu*, B. Guiselin*, N. Bain, I. Zuriguel, and D. Bartolo. ``Emergence of collective oscillations powered by odd friction in massive crowds''. Submitted (2024).
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Seminars (3)
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Séminaire PMMH - Dominic Vella (University of Oxford)
Vendredi 22 mars de 11h00 à 12h00 - Salle réunion PMMH 1
Drops with deformable boundaries : Flat tops, Locomotion and Ageing
A liquid droplet placed on a rigid, planar surface has a captivating simplicity : its surface is a spherical cap and remains in equilibrium. In this talk, I'll show that the addition of a deformable boundary leads to a range of new phenomena : evaporating droplets with an elastic skin may develop flat tops, while (...) -
Séminaire PMMH - Alex Hansen (NTNU Norvège)
Vendredi 29 mars de 11h00 à 12h00 - Salle réunion PMMH 1
Séminaire d'Alex Hansen (NTNU, Trondheim, Norvège)
The co-moving velocity, a new concept in immiscible two-phase flow in porous media Alex Hansen PoreLab, Department of Physics, NTNU, Trondheim, Norway Since 1936, relative permeability theory has been the leading description of immiscible two-phase flow in porous media at scales much larger than the pore scale. (...) -
Séminaire PMMH - Olivier Plé (LOCIE-CNRS)
Vendredi 5 avril de 11h00 à 12h00 - Salle réunion PMMH 1
Rammed earth : A complex medium
Rammed earth is a complex material which is attractive nowadays in construction because of its small environmental footprint. However, this material has specific characteristics, especially : its sensitivity to water, its low mechanical static capacity but a fairly good seismic performance, its high thermal (...)
The audience is composed of people with rather heterogeneous backgrounds including specialists in solids, fluids, granular flows, statistical physics... so the idea is to keep your talk understandable by people not necessarily working in your field... The seminar time slot runs from 11am to noon so the best is to make the talk last around 45 minutes to leave some time for discussion.
- Séminaires ESPCI-ENS de biophysique
- Séminaires du Département de Physique de l’ENS
- Séminaires du Laboratoire d’Hydrodynamique de l’X
- Séminaire de Mécanique d’Orsay (page web FAST)
- Séminaire de Mécanique d’Orsay (page web LIMSI)
- Séminaire de Mécanique des Fluides de l’Institut Jean le Rond d’Alembert
- Séminaires du laboratoire MSC, Paris VII
- Séminaires Gulliver
Link to cofee seminar (internal, every Thursday)
