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Filament mechanics in a half-space via regularised Stokeslet segments

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)808-833
Number of pages26
JournalJournal of Fluid Mechanics
Volume879
Early online date1 Oct 2019
DOIs
DateAccepted/In press - 28 Aug 2019
DateE-pub ahead of print - 1 Oct 2019
DatePublished (current) - 25 Nov 2019

Abstract

We present a generalisation of efficient numerical frameworks for modelling fluid-filament interactions via the discretisation of a recently developed, non-local integral equation formulation to incorporate regularised Stokeslets with half-space boundary conditions, as motivated by the importance of confining geometries in many applications. We proceed to utilise this framework to examine the drag on slender inextensible filaments moving near a boundary, firstly with a relatively simple example, evaluating the accuracy of resistive force theories near boundaries using regularised Stokeslet segments. This highlights that resistive force theories do not accurately quantify filament dynamics in a range of circumstances, even with analytical corrections for the boundary. However, there is the notable and important exception of movement in a plane parallel to the boundary, where accuracy is maintained. In particular, this justifies the judicious use of resistive force theories in examining the mechanics of filaments and monoflagellate microswimmers with planar flagellar patterns moving parallel to boundaries. We proceed to apply the numerical framework developed here to consider how filament elastohydrodynamics can impact drag near a boundary, analysing in detail the complex responses of a passive cantilevered filament to an oscillatory flow. In particular, we document the emergence of an asymmetric periodic beating in passive filaments in particular parameter regimes, which are remarkably similar to the power and reverse strokes exhibited by motile cilia. Furthermore, these changes in the morphology of the filament beating, arising from the fluid-structure interactions, also induce a significant increase in the hydrodynamic drag of the filament.

    Research areas

  • micro-organism dynamics

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via Cambridge University Press at https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/filament-mechanics-in-a-halfspace-via-regularised-stokeslet-segments/03841873F43ADC888DEBDD772C5B2EA1 . Please refer to any applicable terms of use of the publisher.

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