Séminaires PMMH

Séminaire PMMH - Site Jussieu

Séminaires café

Contact :
Benoit Semin
Sylvain Patinet
Etienne Reyssat
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

Comment venir ?

7 quai Saint Bernard, 75005 PARIS

Le séminaire hebdomadaire du laboratoire PMMH a lieu tous les vendredis à 11h, au premier étage Barre Cassan, campus Jussieu.


Séminaire PMMH - David Saintillan (University of California San Diego)

Vendredi 20 septembre 11:00-12:00 - Salle réunion PMMH 1

Viscous dynamics of passive and active microfilaments

Elastic filaments and semiflexible polymers are ubiquitous in biology, where they play a role in cell mechanics and locomotion as well as for fluid transport on the microscale. In this talk, I will discuss two problems involving the interaction of such filaments with fluid flows. The first problem focuses on the dynamics of passive elastic fibers in compressional flow. Experiments performed at ESPCI reveal that these semiflexible polymers buckle under sufficiently strong flows in presence of compressive viscous forces. The buckling induces a spontaneous symmetry breaking that leads to formation of helicoidal morphologies. I will discuss our detailed simulations that reproduce the experimental observations and mention scaling arguments that help to characterize the emerging morphologies. I will then outline a weakly nonlinear theory of post-buckling mode interaction that explains how free filaments spontaneously form helices and highlights why helical coiling is so ubiquitous in strain-dominated flows. In the second problem, I will describe a microscopic model of the flagellar axoneme that retains the essential structural details and incorporates the physics of molecular motors. Under sufficiently high activity of the molecular motors, these active filaments undergo a Hopf bifurcation that leads to spontaneous oscillations. Our model is able to capture various beating patterns ranging from sperm like waveforms to cilia and Chlamydomonas. Using this model we study elasto-hydrodynamic synchronization between filaments. Our computations reveal various conditions where both in-phase and anti-phase synchrony can emerge and elucidate the mechanism for phase slips due to biochemical noise. Model predictions agree with recent experiments and illuminate the crucial roles of hydrodynamics in synchronization

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Séminaires récents  (5)

  • Séminaire PMMH, Vinod Kumar Saranathan (Yale NUS College)
    Vendredi 6 décembre 11:00-12:00 - Salle réunion PMMH 1
    Biomimetic and Bio-inspired Potential of Self-assembled Biophotonic Nanostructures
    Colors in Nature can be produced either chemically, by the selective light bsorption by pigments, or physically, by light interference from biophotonic nanostructures. Intriguingly, there are almost no known violet, blue or green pigments in animals. And yet these structurally produced colors are ubiquitous in (...)
  • Séminaire PMMH — Miguel Fernandez (équipe-projet Commedia, INRIA Paris)
    Vendredi 22 novembre 11:00-12:00 - Salle réunion PMMH 1
    Numerical methods for fluid-structure interaction with immersed elastic bodies
    The mechanical interaction of an incompressible fluid flow with an elastic structure is a multi-physic problem omnipresent in nature and in many engineering fields. One can think, for instance, of the opening/closing dynamics of heart valves when blood is propelled into the arteries and of the wings of a bird (...)
  • Séminaire PMMH - Jérôme Fresnais (PHENIX, UPMC)
    Vendredi 15 novembre 11:00-12:00 - Salle réunion PMMH 1
    Making superhydrophobic surfaces with magnetic elastomer : towards controlled droplet movement
    In the field of superhydrophobic surfaces, natural surfaces exhibiting non-wetting filament networks remain a challenge to understand. Indeed, if classical superhydrophobic surfaces developed roughness at different scales, superhydrophobicity on hairy surfaces shows elastic behavior that is more difficult to (...)
  • Séminaire PMMH -Julien Bobroff (LPS, Univ. Paris-Sud/Paris-Saclay)
    Vendredi 8 novembre 11:00-12:00 - Salle réunion PMMH 1
    La physique autrement
    Pourquoi vulgariser la physique autrement ? Et surtout comment ? Voilà les deux questions au coeur des activités de notre équipe de recherche. Nous y explorons de nouvelles formes de vulgarisation en lien avec le monde du design et de la création. Parmi nos dernières productions, un objet de médiation sur la (...)
  • Séminaire PMMH- Pedro Saenz (University of North Carolina at Chapel Hill)
    Vendredi 25 octobre 11:00-12:00 - Salle réunion PMMH 1
    Hydrodynamic Spin Lattices
    Mesoscale and macroscale analogs of electronic spin systems, such as ultra-cold fermionic lattice gases and mechanical metamaterials, offer direct insights into fundamental physical prin ciples while simultaneously promising groundbreaking applications, from quantum computation and simulators to photonic and (...)

Instructions générales pour les conférenciers

Le public du séminaire est très hétérogène (rien qu’au PMMH nous travaillons sur des thématiques très diverses, mécanique des fluides, des milieux granulaires, des solides, physique statistique, physique du mouillage, micro-fluidique, biophysique,...) l’objectif est donc de ne pas faire un séminaire trop spécialiste : au moins la première moitié du séminaire à un niveau accessible pour celui qui ne connaît rien sur le sujet.

Le séminaire a lieu à 11h. rendez-vous 15 minutes avant pour installer et tester la projection.

Le séminaire dure environ 45 minutes pour laisser un peu de temps pour discuter à la fin.

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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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