Fluid­–body interactions in passive and active liquid crystals

Fluid anisotropy, or direction-dependent response to deformation, can be observed in biofluids like mucus or, at a larger scale, self-aligning swarms of active bacteria. A model fluid used to investigate such environments is a nematic liquid crystal. Large colloidal particles undergo shape-dependent interactions when immersed in such fluids, whilst many microorganisms must propel themselves through these complex environments. Furthermore, the interaction between these active swimmers and passive particles gives rise to active stresses. In this talk, we will bring the power of complex variables to bear on this problem, in order to analytically solve for the interactions inside a liquid crystalline environment. This approach allows for the solution of a wide range of problems, opening the door to studying the role of body shape and orientation, liquid crystal anchoring conditions, and body deformability. Shape-dependent forces between bodies, local tractions, and active stresses will all be discussed.