Digitized gait of C. elegans' head: from mixing to propulsion*

 A naturally inspired way of propulsion and mixing in low Reynolds number conditions is to replicate the locomotory function of microorganisms that have evolved to swim in highly viscous environments. Nematoda is an example of such microorganisms, and artificial mechanisms that mimic the locomotory functions of nematodes can be efficient viscous pumps. Here we simulate the motion of the head segment of Caenorhabditis elegans by introducing a reciprocating and rocking blade. We experimentally and numerically show that the bio-inspired blade’s motion not only induces a flow structure similar to that of the worm, but also chaotically mixes the surrounding fluid by generating a circulatory flow. When confined between two parallel walls, the blade causes a steady Poiseuille flow with a pumping efficiency comparable with the swimming efficiency of the worm.