Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, Epiciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Unsteady feeding and optimal strokes of model ciliates

Abstract : The flow field created by swimming micro-organisms not only enables their locomotion but also leads to advective transport of nutrients. In this paper we address analytically and computationally the link between unsteady feeding and unsteady swimming on a model micro-organism, the spherical squirmer, actuating the fluid in a time-periodic manner. We start by performing asymptotic calculations at low Peclet number (Pe) on the advection-diffusion problem for the nutrients. We show that the mean rate of feeding as well as its fluctuations in time depend only on the swimming modes of the squirmer up to order Pe(3/2), even when no swimming occurs on average, while the influence of non-swimming modes comes in only at order Pe(2). We also show that generically we expect a phase delay between feeding and swimming of 1/8th of a period. Numerical computations for illustrative strokes at finite P e confirm quantitatively our analytical results linking swimming and feeding. We finally derive, and use, an adjoint-based optimization algorithm to determine the optimal unsteady strokes maximizing feeding rate for a fixed energy budget. The overall optimal feeder is always the optimal steady swimmer. Within the set of time-periodic strokes, the optimal feeding strokes are found to be equivalent to those optimizing periodic swimming for all values of the Peclet number, and correspond to a regularization of the overall steady optimal.
Complete list of metadata

Cited literature [29 references]  Display  Hide  Download
Contributor : Denis Roura Connect in order to contact the contributor
Submitted on : Tuesday, June 3, 2014 - 9:17:09 PM
Last modification on : Thursday, August 26, 2021 - 1:34:02 PM
Long-term archiving on: : Wednesday, September 3, 2014 - 10:55:18 AM


Publisher files allowed on an open archive




Sebastien Michelin, Eric Lauga. Unsteady feeding and optimal strokes of model ciliates. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2013, 715, pp.1-31. ⟨10.1017/jfm.2012.484⟩. ⟨hal-00996495⟩



Record views


Files downloads