Efficient simulation of filament elastohydrodynamics in three dimensions

Fluid-structure simulations of slender inextensible filaments in a viscous fluid are
often plagued by numerical stiffness. Recent coarse-graining studies have reduced the
computational requirements of simulating such systems, though they have thus far been
limited to the motion of planar filaments. In this paper we extend such frameworks to
filament motion in three dimensions, identifying and circumventing coordinate-system
singularities introduced by filament parametrization via repeated changes of basis. The
resulting methodology enables efficient and rapid study of the motion of flexible filaments
in three dimensions, and is readily extensible to a wide range of problems, including
filament motion in confined geometries, large-scale active matter simulations, and the
motility of mammalian spermatozoa.