No net motion for oscillating near-spheres at low Reynolds numbers

Noisy swimming at low Reynolds numbers.

Small organisms (e.g., bacteria) and artificial microswimmers move due to a combination of active swimming and passive Brownian motion. Considering a simplified linear three-sphere swimmer, we study how the swimmer size regulates the interplay between self-driven and diffusive behavior at low Reynolds number. Starting from the Kirkwood-Smoluchowski equation and its corresponding Langevin equati...

Shear layer instability at low reynolds numbers

Optimal swimming at low Reynolds numbers.

Efficient swimming at low Reynolds numbers is a major concern of microbots. To compare the efficiencies of different swimmers we introduce the notion of "a swimming drag coefficient" which allows for the ranking of swimmers. We find the optimal swimmer within a certain class of two-dimensional swimmers using conformal mapping techniques.

Friction coefficient of rod-like chains of spheres at very low Reynolds numbers. I. Experiment

We present a new method to measure hydrodynamic friction forces on colloidal particles at very low (ci 10~~) Reynolds numbers with high accuracy. Exploiting magnetic field induced aggregation of microcopic paramagnetic spheres into straight chains of calibrated length, we determine the anisotropic friction coefficient of the chains, with a range from one to 100 particles, by video-microscopic o...

Unsteady aerodynamic models for agile flight at low Reynolds numbers

The goal of this work is to develop low-order models for the unsteady aerodynamic forces on a small wing in response to agile maneuvers and gusts. In a previous study, it was shown that Theodorsen’s and Wagner’s unsteady aerodynamic models agree with force data from DNS for pitching and plunging maneuvers of a 2D flat plate at Reynolds numbers between 100 and 300 as long as the reduced frequenc...