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DY: Fachverband Dynamik und Statistische Physik
DY 54: Microswimmers, Active Liquids - Part II (joint session CPP/ BP/ DY)
DY 54.1: Invited Talk
Thursday, March 19, 2015, 15:45–16:15, PC 203
Flagellar synchronisation through direct hydrodynamic interactions — •Marco Polin1, Douglas Brumley2, Kirsty Wan3, and Raymond Goldstein3 — 1University of Warwick, Coventry. UK — 2MIT, Boston, MA. US — 3University of Cambridge, Cambridge. UK
Microscale fluid flows generated by ensembles of beating eukaryotic flagella are crucial to fundamental processes such as development, motility and sensing. Despite significant experimental and theoretical progress, the underlying physical mechanisms behind this striking coordination remain unclear. We describe a novel series of experiments in which the flagellar dynamics of two micropipette-held somatic cells of Volvox carteri, with measurably different intrinsic beating frequencies, are studied by high-speed imaging as a function of their mutual separation and orientation. From analysis of beating time series, we find that the interflagellar coupling, which is constrained by the lack of chemical and mechanical connections between the cells to be purely hydrodynamical, exhibits a spatial dependence that is consistent with theoretical predictions. At close spacings it produces robust synchrony which can prevail for thousands of flagellar beats, while at increasing separations this synchrony is systematically degraded by stochastic processes. Through dynamic flagellar tracking we quantify the associated waveforms and show that they are significantly different in the synchronised state. This study unequivocally reveals that flagella coupled only through a fluid medium are capable of exhibiting robust synchrony despite significant differences in their intrinsic properties.