Lord Kelvin's isotropic helicoid

Nearly 150 years ago, Lord Kelvin proposed the isotropic helicoid, a particle with isotropic yet chiral interactions with a fluid, so that translation couples to rotation. An implementation of his design fabricated with a three-dimensional printer is found experimentally to have no detectable transl...

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Bibliographic Details
Published in:arXiv.org 2021-07
Main Authors: Collins, Darci, Hamati, Rami J, Candelier, Fabien, Gustavsson, Kristian, Mehlig, Bernhard, Voth, Greg A
Format: Article
Language:English
Subjects:
Coupling
Fluid dynamics
Rotation
Stokes flow
Symmetry
Three dimensional printing
Vanes
Online Access:Get full text
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Summary:Nearly 150 years ago, Lord Kelvin proposed the isotropic helicoid, a particle with isotropic yet chiral interactions with a fluid, so that translation couples to rotation. An implementation of his design fabricated with a three-dimensional printer is found experimentally to have no detectable translation-rotation coupling, although the particle point-group symmetry allows this coupling. We explain these results by demonstrating that in Stokes flow, the chiral coupling of such isotropic helicoids made out of non-chiral vanes is due only to hydrodynamic interactions between these vanes. Therefore it is small. In summary, Kelvin's predicted isotropic helicoid exists, but only as a weak breaking of a symmetry of non-interacting vanes in Stokes flow.
ISSN:2331-8422
DOI:10.48550/arxiv.2006.08282