Hydrodynamic interaction of two swimming model micro-organisms
In order to understand the rheological and transport properties of a suspension of swimming micro-organisms, it is necessary to analyse the fluid-dynamical interaction of pairs of such swimming cells. In this paper, a swimming micro-organism is modelled as a squirming sphere with prescribed tangenti...
Saved in:
Published in | Journal of fluid mechanics Vol. 568; pp. 119 - 160 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Cambridge, UK
Cambridge University Press
10.12.2006
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | In order to understand the rheological and transport properties of a suspension of swimming micro-organisms, it is necessary to analyse the fluid-dynamical interaction of pairs of such swimming cells. In this paper, a swimming micro-organism is modelled as a squirming sphere with prescribed tangential surface velocity, referred to as a squirmer. The centre of mass of the sphere may be displaced from the geometric centre (bottom-heaviness). The effects of inertia and Brownian motion are neglected, because real micro-organisms swim at very low Reynolds numbers but are too large for Brownian effects to be important. The interaction of two squirmers is calculated analytically for the limits of small and large separations and is also calculated numerically using a boundary-element method. The analytical and the numerical results for the translational–rotational velocities and for the stresslet of two squirmers correspond very well. We sought to generate a database for an interacting pair of squirmers from which one can easily predict the motion of a collection of squirmers. The behaviour of two interacting squirmers is discussed phenomenologically, too. The results for the trajectories of two squirmers show that first the squirmers attract each other, then they change their orientation dramatically when they are in near contact and finally they separate from each other. The effect of bottom-heaviness is considerable. Restricting the trajectories to two dimensions is shown to give misleading results. Some movies of interacting squirmers are available with the online version of the paper. |
---|---|
Bibliography: | ark:/67375/6GQ-N08NJCRL-5 istex:E4CF93E5C324F85FB70696590697E2ABEB6CAE5F PII:S0022112006002631 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0022-1120 1469-7645 |
DOI: | 10.1017/S0022112006002631 |