Generalized Taylor dispersion of chiral microswimmers.

Transport phenomena of microswimmers in fluid flows play a crucial role in various biological processes, including bioconvection and cell sorting. In this article, we investigate the dispersion behaviour of chiral microswimmers in a simple shear flow using the generalized Taylor dispersion theory, inspired by biased locomotion of bacterial rheotaxis swimmers. We thus focused on the influence of shear-induced torque effects due to particle chirality, employing an extended Jeffery equation for individual deterministic dynamics. We then numerically calculated macroscopic parameters, including the average swimming velocity and the effective diffusion tensor using spherical harmonic expansion, and evaluated the obtained results based on the fixed points and the stability of the orientational dynamical systems. Our results reveal that chiral effects induce biased locomotion, and we observed qualitative transitions in the orientational distribution with increasing Péclet number, consistent with previous experimental findings. The diffusion tensor analysis highlighted a significant reduction in the diffusion coefficient perpendicular to the shear plane due to chirality. This suggests potential applications in flow-mediated cell separation, and we numerically demonstrated such chirality-induced fluid transport.This article is part of the theme issue 'Biological fluid dynamics: emerging directions'.