Seminars

PMMH’s weekly seminar is held every Friday at 11 am (map)

Contact :
Sylvain Patinet
Stéphane Perrard
Etienne Reyssat
Virgile Thiévenaz
responsables-seminaires (arobase) pmmh.espci.fr

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

Vendredi 12 avril de 11h00 à 12h00 - Salle réunion PMMH 1

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  (5)

  • Séminaire PMMH - François Petrelis (ENS)
    Vendredi 31 mai de 11h00 à 12h00 - Salle réunion PMMH 1
    Earthquake statistical properties : an explanation for the distribution of magnitude and for the existence of aftershocks
    Earthquakes in nature follow several statistical properties. In particular, the distribution of energy released by an earthquake (Gutenberg-Richter's law) and the frequency of aftershocks after a large event (Omori's law) are both power-laws. By studying several earthquake models, we have shown that the (...)
  • Séminaire PMMH - Ko Okumura (Ochanomizu University, Tokyo)
    Vendredi 14 juin de 11h00 à 12h00 - Salle réunion PMMH 1
    A hydrodynamic analog of critical phenomena : an uncountably infinite number of universality classes
    When a solid object starts falling into a viscous fluid from air-liquid interface, air is entrained into the liquid and eventually detaches from the solid. Such detachment could occur with or without topological change. Recently, it was found that the former case (i.e., breakup, a form of singular transitions) is (...)
  • Séminaire PMMH - Ko Okumura (Ochanomizu University, Tokyo)
    Vendredi 14 juin de 11h00 à 12h00 - Salle réunion PMMH 1
    A hydrodynamic analog of critical phenomena : an uncountably infinite number of universality classes
    When a solid object starts falling into a viscous fluid from air-liquid interface, air is entrained into the liquid and eventually detaches from the solid. Such detachment could occur with or without topological change. Recently, it was found that the former case (i.e., breakup, a form of singular transitions) is (...)
  • Séminaire PMMH - Avin Babataheri (Ladhyx)
    Vendredi 20 septembre de 11h00 à 12h00 - Salle réunion PMMH 1
    1D confinement controls cell shape and migration
    Pericytes are mural cells of the microvasculature, they wrap around small vessels, support the vessels mechanically and participate in blood flow regulation. Pericytes are distinguished by two main characteristics ; first their distinct morphology, which has been likened to a “bump on a log”, as they present long (...)
  • Séminaire PMMH - Avin Babataheri (Ladhyx)
    Vendredi 20 septembre de 11h00 à 12h00 - Salle réunion PMMH 1
    1D confinement controls cell shape and migration
    Pericytes are mural cells of the microvasculature, they wrap around small vessels, support the vessels mechanically and participate in blood flow regulation. Pericytes are distinguished by two main characteristics ; first their distinct morphology, which has been likened to a “bump on a log”, as they present long (...)
Information for the speakers

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.

Link to cofee seminar (internal, every Thursday)


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Practical information

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