Active particles contain internal degrees of freedom with the ability to take in and dissipate
energy and, in the process, execute systematic movement. Examples include all living …

We review the literature on swimming in complex fluids. A classification is proposed by
comparing the length-and timescales of a swimmer with those of nearby obstacles …

Active colloids are microscopic particles, which self-propel through viscous fluids by
converting energy extracted from their environment into directed motion. We first explain …

Bacterial processes ranging from gene expression to motility and biofilm formation are
constantly challenged by internal and external noise. While the importance of stochastic …

We study the collective motion of confined spherical microswimmers such as active colloids
which we model by so-called squirmers. To simulate hydrodynamic flow fields including …

Experimental observations indicate that, at sufficiently high cell densities, swimming bacteria
exhibit coordinated motions on length scales (10 to 100 μm) that are large compared with …

The spherical alga Volvox swims by means of flagella on thousands of surface somatic cells.
This geometry and its large size make it a model organism for studying the fluid dynamics of …

The fluid dynamics of microswimmers has received attention from the fields of microbiology,
microrobotics, and active matter. Microorganisms have evolved organelles termed cilia for …

Active suspensions, such as suspensions of self-propelled microorganisms and related
synthetic microswimmers, are known to undergo complex dynamics and pattern formation as …

The hydrodynamics of an archetypal low-Reynolds number swimmer, called “squirmer,”
near a wall has been numerically studied. For a single squirmer, depending on the …