2 The UK Department for International Development (DFID) supports policies, programmes and projects to promote poverty reduction globally. DFID provided funds for this study as part of that goal but the views and opinions expressed are those of the author(s) alone. This paper may be reproduced free of charge in any format provided the source is acknowledged.
We investigate the hydrodynamic interactions between micro-organisms swimming at low Reynolds number. By considering simple model swimmers, and combining analytic and numerical approaches, we investigate the time-averaged flow field around a swimmer. At short distances the swimmer behaves like a pump. At large distances the velocity field depends on whether… (More)
The authors employ three numerical methods to explore the motion of low Reynolds number swimmers, modeling the hydrodynamic interactions by means of the Oseen tensor approximation, lattice Boltzmann simulations, and multiparticle collision dynamics. By applying the methods to a three bead linear swimmer, for which exact results are known, the authors are… (More)
We describe in detail the hydrodynamics of a simple model of linked sphere swimmers. We calculate the asymptotic form of both the time averaged flow field generated by a single swimmer and the interactions between swimmers in a dilute suspension, showing how each depends on the parameters describing the swimmer and its swimming stroke. We emphasize the… (More)
Simulations of liquid-gas systems with interface terms evaluated by central difference discretizations are observed to fail to give accurate results for two reasons: the interface can get "stuck" on the lattice or a density overshoot develops around the interface. In the first case, the bulk densities can take a range of values, dependent on the initial… (More)
We use a three-dimensional lattice Boltzmann model to investigate the spreading of mesoscale droplets on homogeneous and heterogeneous surfaces. On a homogeneous substrate the base radius of the droplet grows with time as t 0.28 for a range of viscosities and surface tensions. The time evolutions collapse onto a single curve as a function of a dimensionless… (More)