Laboratoire Matière et Systèmes Complexes

March 8th 2021. 11h30

There will be a live diffusion with Zoom. Contact Michael Berhanu to attend the video seminar.

Spreading : from the atomic bomb to cell motility

Marc-Antoine Fardin

Institut Jacques Monod, Équipe Adhésion cellulaire et mécanique

CNRS, Université de Paris

Abstract : The method Taylor once used to derive the energy of an atomic bomb from the spreading of the blast is a well known example of dimensional analysis. If used with care, such approach can be applied to derive a vast array of spreading regimes, from supernova blasts to droplets or cells. With some colleagues, we are currently writing a review of spreading from the perspective of dimensional analysis, highlighting the strength of the method as well as its limitations. I will present some of the examples we have chosen. In the process of putting together this review, we found that it was useful to tabulate all "mass-carrying" quantities with dimensions of the form M.L^a.T^b, where a and b are small integers. For instance, Taylor’s spreading regime corresponds to a balance between an energy [E]=M.L^2.T^-2, and density [rho]=M.L^-3. Mass, action, momentum, viscosity, force, pressure, power, etc., these mass-carrying quantities encompass most of the colloquial "forces" at play during various spreadings. I will present a table of these quantities and ask for your input on how to augment and improve it. We believe that such table can not only be useful for researchers interested in spreading, but also for teachers and students of physics trying to convey or learn the ways in which the many physical quantities can interact with one another.