ANALYSE EXPERIMENTALE DE LA DYNAMIQUE DE NAGE DES SPERMATOZOIDES Directeur(s) de Thèse : Membre(s) du jury

Mécanique, M Franck, Plouraboue Olivier, Praud Rapporteurs, Anke Mme, Espci Lindner, M Paris, Hermes Gadelha, M Praud, Inp Toulouse, Membre Degond
unpublished
Collective motion of self-sustained swarming flows has recently provided examples of small-scale turbulence arising where viscous effects are dominant. We report the first observation of universal enstrophy cascade in concentrated swarming sperm consistent with a body of evidence built from various independent measurements. We found a well-defined k −3 power-law decay of a velocity field power spectrum and relative dispersion of small beads consistent with theoretical predictions in 2D
more » ... e. Concentrated living sperm displays long-range, correlated whirlpool structures of a size that provides an integral scale of turbulence. We propose a consistent explanation for this quasi-2D turbulence based on self-structured laminated flow forced by steric interactions and alignment, a state of active matter that we call "swarming liquid crystal." We develop scaling arguments consistent with this interpretation.
fatcat:q2hrlrpe5vcwzpovqez66rdl2i