Transport of fibres in surface waves

Fibres from the breakdown of clothing, fishing lines, and other debris are dispersed in lakes and oceans by surface waves. We examine fibre transport in waves via models that take into account inertial effects in successive approximations of slender body. We use these models to explore how fibre properties (i.e., length, diameter, desnity) and orientation influence fibre transport under different wave conditions. We find solutions to the fibre transport in terms of drift velocities that are analogues of the classical Stokes drift. We find that inertialess slender body theory predicts that neutrally buoyant fibres drift at the same rate as the Stokes drift irrespective of fibre properties, since wave-induced flow is dominated by a single length scale. However, this picture is altered as both fibre and fluid inertia become important. Our results show that, counter intuitively, fibre transport is enhanced by inertial effects.