Kinematic irreversibility in surfactant-laden interfaces
Abstract
The surface shear viscosity of an insoluble surfactant monolayer often depends strongly on its surface pressure. Here, we show that a particle moving within a bounded monolayer breaks the kinematic reversibility of low-Reynolds-number flows. The Lorentz reciprocal theorem allows such irreversibilities to be computed without solving the full nonlinear equations, giving the leading-order contribution of surface-pressure-dependent surface viscosity. In particular, we show that a disk translating or rotating near an interfacial boundary experiences a force in the direction perpendicular to that boundary. In unbounded monolayers, coupled modes of motion can also lead to non-intuitive trajectories, which we illustrate using an interfacial analog of the Magnus effect. This perturbative approach can be extended to more complex geometries, and to 2D suspensions more generally.
Cite
@article{arxiv.1705.05978,
title = {Kinematic irreversibility in surfactant-laden interfaces},
author = {Harishankar Manikantan and Todd M. Squires},
journal= {arXiv preprint arXiv:1705.05978},
year = {2017}
}