From hydrodynamic lubrication to many-body interactions in dense suspensions of active swimmers

Many-body hydrodynamic interactions in charge-stabilized suspensions.

In this joint experimental-theoretical work we study hydrodynamic interaction effects in dense suspensions of charged colloidal spheres. Using x-ray photon correlation spectroscopy we have determined the hydrodynamic function H(q), for a varying range of electrosteric repulsion. We show that H(q) can be quantitatively described by means of a novel Stokesian dynamics simulation method for charge...

Micro-swimmers with hydrodynamic interactions

The low-Reynolds number motions of Purcell’s three-link swimmer, and of a closely-related two-paddle swimmer, are investigated and compared using slender-body theory and resistive-force theory. The results are compared (in the case of the three-link swimmer) with the resistive-force calculations of Becker, Koehler and Stone (BKS). In particular, we examine the effect of hydrodynamic interaction...

Transition from Boundary Lubrication to Hydrodynamic Lubrication of Slider Bearings

The transition from boundary lubrication to fully hydrodynamic lubrication is investigated for air-lubricated slider bearings using the electrical resistance method. Intermittent contacts are shown to exist even under conditions for which the numerical solution of the Reynolds equation or white light interferometry predicts steady state spacings in the spacing region from 0.125 to 0.25 pm. The ...

Propagation of hydrodynamic interactions in colloidal suspensions.

We describe direct measurements of the dynamics of two colloidal spheres before hydrodynamic interactions have had time to fully develop. We find that the dynamics of the two spheres are coupled at times significantly shorter than tau(nu), the time required for vorticity to diffuse between the two spheres. From the distance dependence of the measured coupling, we infer that hydrodynamic interac...

Flowing resistance and dilatancy of dense suspensions: lubrication and repulsion