Abstract

A key feature of active fluids is their ability to self-organize into spontaneous flow patterns. In this talk, I will first discuss the transition from laminar to chaotic flows in active fluids, known as active turbulence. I will show that, unlike in the classic scenario of directed percolation in pipe flow, the transition to turbulence in boundaryless active nematics is discontinuous, and that this is due to the long-range hydrodynamic interactions of Stokes flow. Second, I will discuss the aggregation and self-organization of bacteria via capillary forces. These forces are produced by water menisci that surround bacteria in hydrated environments like soil, textiles and agar hydrogels in the lab. Finally, I will discuss the emergence of active surface waves on multilayered bacterial colonies.