Propulsive force measurements and flow behavior of undulatory swimmers at low Reynolds number

Abstract

The swimming behavior of the nematode Caenorhabditis elegans is investigated in aqueous solutions of increasing viscosity. Detailed flow dynamics associated with the nematode's swimming motion as well as propulsive force and power are obtained using particle tracking and velocimetry methods. We find that C. elegans delivers propulsive thrusts on the order of a few nanonewtons. Such findings are supported by values obtained using resistive force theory; the ratio of normal to tangential drag coefficients is estimated to be approximately 1.4. Over the range of solutions investigated here, the flow properties remain largely independent of viscosity. Velocity magnitudes of the flow away from the nematode body decay rapidly within less than a body length and collapse onto a single master curve. Overall, our findings support that C. elegans is an attractive living model to study the coupling between small-scale propulsion and low Reynolds number hydrodynamics. The swimming behavior of the nematode Caenorhabditis elegans is investigated in aqueous solutions of increasing viscosity. Detailed flow dynamics associated with the nematode's swimming motion as well as propulsive force and power are obtained using particle tracking and velocimetry methods. We find that C. elegans delivers propulsive thrusts on the order of a few nanonewtons. Such findings are supported by values obtained using resistive force theory; the ratio of normal to tangential drag coefficients is estimated to be approximately 1.4. Over the range of solutions investigated here, the flow properties remain largely independent of viscosity. Velocity magnitudes of the flow away from the nematode body decay rapidly within less than a body length and collapse onto a single master curve. Overall, our findings support that C. elegans is an attractive living model to study the coupling between small-scale propulsion and low Reynolds number hydrodynamics. Disciplines Engineering | Mechanical Engineering

Characterizations of kinetic power and propulsion of the nematode Caenorhabditis elegans based on a micro-particle image velocimetry system

“…However, the sinusoidal waveform is typically a theoretical model, which may inevitably introduce deviations from the reality. Our findings 8 and prior research 2,9 have shown that C. elegans tends to vary its swimming gait in response to the ambient viscosity. Nevertheless, the same theory was later adopted by some research groups to study the nematode neurobiology and behavior 10 phenotype.…”

“…A medium with viscosity of 10 mPa s was made by mixing dextran (FL-95771/MW ¼ 2 000 000, Sigma) with the NGM buffer to achieve a 6% dextran solution. Numerous studies 2,8,9,31 have reported that C. elegans is able to sense the ambient viscosity change and make a behavioral response according to the coordination between sensory and motor neurons. A representative trajectory of movement and a relationship of power and propulsion similar to the previous N2 and kin-2 are depicted in Figs.…”

“…Their results suggested that C. elegans locomotory gait continuously adapts to external mechanical load in order to maintain propulsive thrust. By contrast, Sznitman et al 9 improved the theoretical calculations by measuring piecewise velocities along the worm's body. For simplicity, the worm was assumed to be a rod with a squared cross-section.…”

Propensity of undulatory swimmers, such as worms, to go against the flow

“…The subscripts U, S, and C denote, respectively, the contributions of the undulatory motion, background flow, and steric Lennard-Jones-like hindrance. We compute M(t), F U,x (t), F U,y (t), F S,x (t), (24,25). As the swimmer approaches the side wall, its head enters a region of low velocity while its tail remains exposed to a higher velocity (t = 2 s).…”

Gait-specific adaptation of locomotor activity in response to dietary restriction inCaenorhabditis elegans

“…Swimming of AL-fed and DR wild-type worms was also determined as a function of the mechanical load using viscous liquids, in which the worms require greater muscle strength to maintain their locomotory rate (Sznitman et al, 2010). Taking into account that DR-fed C. elegans display an ~60% lower protein content, most likely a proxy for muscle mass, than AL-fed worms (Fig.…”