Active jamming of microswimmers at a bottleneck constriction

Abstract

A study of the light-induced evacuation of a suspension of microwimmers (the micro-alga Chlamydomonas reinhardtii) through a bottleneck-shaped constriction is presented. We show that a transition from a jammed phase to an uninterrupted phase occurs when varying either the door size or the swimming velocity. The survival function of exit times is then found to evolve from a power law to an exponential trend. Moreover, we found that the evacuation time increases with increasing velocity, a behavior reminiscent of the ``faster-is-slower'' paradox present in crowd dynamics systems.