| | Jason Picardo (IIT Bombay) | | | | How linear relaxation triggers nonlinear waves in an active fluid | | | | Below the plasma membrane of every eukaryotic cell resides the actomyosin cortex,
a thin layer of actin filaments and myosin molecular motors, which behaves like an
active fluid film and is the site of fascinating morphogenetic processes. The
fundamental mechanochemical feedback—an active scalar (myosin motors) generates
contractile forces within the film which drive flows that in turn redistribute the scalar—
may be described by a simple one dimensional model, consisting of the advection-
diffusion-reaction equation and the creeping flow Stokes equation. While this model
gives rise to stationary patterned states via a linear instability, it has hitherto been
thought that it is insufficient to explain the wave-like patterns observed in experiments.
In this work, we show and explain how the inclusion of a simple linear reaction, which
causes concentration perturbations to relax (and models turnover of the cortex), can
surprisingly trigger the onset of waves via a secondary bifurcation. The waves arise
due to an interplay between different spatial modes of the concentration field; we
elucidate this nonlinear inter-mode interaction, and the crucial role of the linear relaxation,
with the help of a Galerkin-truncated reduced-order model. These waves represent a
new paradigm of mechano-chemical pulsatory pattern formation and are insensitive to
changes in the domain: we find these waves in both one and two dimensional domains,
with either periodic or no-flux boundaries, and even on a sphere.
Collaborator: K. Vijay Kumar, ICTS-TIFR, Bangalore, India | | | | E-mail: https://www.che.iitb.ac.in/faculty/jason-r-picardo | | Gestion: Florence |
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| | Colm Caulfield (University of Cambridge) | | | | Rencontres Niçoises de Méca Flu | | | | | | | | Gestion: Florence |
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| | Alain Blaustein (Pennsylvania State University) | | | | TBA | | | | | | |
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| 06/06/2024 | | | | 11h | | | | Salle Fizeau | | |
| | Salma Lahbabi (Université de Casablanca) | | | | | | | | | | |
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| 13/06/2024 | | | | 11:00 | | | | Salle de conférence | | |
| | Philippe Hoch (CEA DAM) | | | | TBA | | | | | | |
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| 20/06/2024 | | | | 11h | | | | Salle de conférences | | |
| | Maxime Herda (Université de Lille) | | | | TBA | | | | | | | | Gestion: Isabelle |
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| | David Hughes () | | | | | | | | | | | | Gestion: Florence |
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| | () | | | | DataHyKing Days | | | | | | | | Gestion: Thomas |
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| | André Galligo ? () | | | | | | | | | | | | Gestion: Isabelle |
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