Taylor dispersion of gyrotactic swimming micro-organisms in a linear flow

Hill, N.A. and Bees, M.A. (2002) Taylor dispersion of gyrotactic swimming micro-organisms in a linear flow. Physics of Fluids, 14(8), pp. 2598-2605. (doi: 10.1063/1.1458003)

Abstract

The theory of generalized Taylor dispersion for suspensions of Brownian particles is developed to study the dispersion of gyrotactic swimming micro-organisms in a linear shear flow. Such creatures are bottom-heavy and experience a gravitational torque which acts to right them when they are tipped away from the vertical. They also suffer a net viscous torque in the presence of a local vorticity field. The orientation of the cells is intrinsically random but the balance of the two torques results in a bias toward a preferred swimming direction. The micro-organisms are sufficiently large that Brownian motion is negligible but their random swimming across streamlines results in a mean velocity together with diffusion. As an example, we consider the case of vertical shear flow and calculate the diffusion coefficients for a suspension of the alga <i>Chlamydomonas nivalis</i>. This rational derivation is compared with earlier approximations for the diffusivity.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hill, Professor Nicholas and Bees, Dr Martin
• Authors: Hill, N.A., and Bees, M.A.
• Subjects: Q Science > QA Mathematics; Q Science > QC Physics
• College/School: College of Science and Engineering > School of Mathematics and Statistics > Mathematics
• Journal Name: Physics of Fluids
• ISSN: 1070-6631
• ISSN (Online): 1089-7666
• Published Online: 18 June 2002