Seminarium Fizyki Politechniki Wrocławskiej
PWr, bud. A1, sala 322
Microswimmers: From design principles to their emergent collective behavior
prof. Holger Stark
Institut für Theoretische Physik, Technische Universität Berlin, Niemcy
Active motion of biological and artificial microswimmers is relevant in the real world, in microfluidics, and biological applications but also poses fundamental questions in non-equilibrium statistical physics. Mechanisms of single microswimmers either designed by nature or in the lab need to be understood and a detailed modeling of microorganisms helps to explore their complex cell design and their behavior. The emergent collective motion of microswimmers generates appealing dynamic patterns as a consequence of the non-equilibrium.
In this talk I review some of our work modeling biological microswimmers such as E. coli and the African trypanosome, the causative agent of the sleeping sickness, in order to contribute to their better understanding. Using simpler model microswimmers, I will demonstrate the richness of their emerging collective behavior. Hydrodynamic simulations with multi-particle collision dynamics show motility-induced phase separation of squirmers and exponential sedimentation profiles under gravity with superimposed large-scale convection. Under strong gravity and at small densities, single layers of squirmers form hydrodynamic Wigner crystals or exhibit swarming depending on the swimmer type. Finally, self-phoretic active colloids are able to sense their environment and perform chemotactic motion mimicking a mechanism important in bacterial systems.
