FIG. 4.

(color online). Waltzing dynamics. Geometry of (a) two interacting Stokeslets (side view) and (b) nearby spinning colonies (top view). (c) Radial separation r, normalized by mean colony radius, as a function of rescaled time for 60 events (black). Running average (green) compares well with predictions of the singularity model (red). Inset shows orbiting frequency Ω as a function of mean spinning frequency $\stackrel{‒}{\omega }$, and linear fit.