Nematode swimming and turning: locomotion of {\it C.\ Elegans} in bulk fluid and thin fluid layers

A millimeter-long nematode {\it C.\ Elegans} propels itself by performing sinous undulations, and it turns by assuming strongly curved $\Omega$-shaped body postures. All these stereotyped motions can accurately be described in terms of piecewise-harmonic body curvature, which propagates backwards along the nematode length [PLoS ONE, 7: e40121 (2012)]. We combine our piecewise-harmonic-curvature description with accurate hydrodynamic bead-chain models to investigate swimming efficiency and maneuverability of the nematode in bulk fluid and in a thin fluid layer. We find that the nematode swims faster and maneuvers more efficiently under confinement, because of a larger transverse hydrodynamic resistance. However, the optimal swimming gate is only weakly affected.