Jump to main content
Jump to site search

Issue 6, 2016
Previous Article Next Article

Deformation of a soft helical filament in an axial flow at low Reynolds number

Author affiliations

Abstract

We perform a numerical investigation of the deformation of a rotating helical filament subjected to an axial flow, under low Reynolds number conditions, motivated by the propulsion of bacteria using helical flagella. Given its slenderness, the helical rod is intrinsically soft and deforms due to the interplay between elastic forces and hydrodynamic loading. We make use of a previously developed and experimentally validated computational tool framework that models the elasticity of the filament using the discrete elastic rod method and the fluid forces are treated using Lighthill's slender body theory. Under axial flow, and in the absence of rotation, the initially helical rod is extended. Above a critical flow speed its configuration comprises a straight portion connected to a localized helix near the free end. When the rod is also rotated about its helical axis, propulsion is only possible in a finite range of angular velocity, with an upper bound that is limited by buckling of the soft helix arising due to viscous stresses. A systematic exploration of the parameter space allows us to quantify regimes for successful propulsion for a number of specific bacteria.

Graphical abstract: Deformation of a soft helical filament in an axial flow at low Reynolds number

Back to tab navigation

Publication details

The article was received on 22 Oct 2015, accepted on 15 Dec 2015 and first published on 16 Dec 2015


Article type: Paper
DOI: 10.1039/C5SM02625C
Author version available: Download Author version (PDF)
Citation: Soft Matter, 2016,12, 1898-1905
  •   Request permissions

    Deformation of a soft helical filament in an axial flow at low Reynolds number

    M. K. Jawed and P. M. Reis, Soft Matter, 2016, 12, 1898
    DOI: 10.1039/C5SM02625C

Search articles by author

Spotlight

Advertisements