Anisotropic Stokes Drag and Dynamic Lift on Spheres Sedimenting in a Nematic Liquid Crystal

The motion of silica spheres with homeotropic anchoring sedimenting within nematic liquid crystal 4-cyano-4′-pentylbiphenyl (5CB) has been studied at low Ericksen number. The magnitude of the spheres’ velocity depends on the angle θ between the far-field nematic director and the gravitational force,...

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Bibliographic Details
Published in:Langmuir 2013-02, Vol.29 (7), p.2104-2107
Main Authors: Rovner, Joel B, Reich, Daniel H, Leheny, Robert L
Format: Article
Language:English
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Summary:The motion of silica spheres with homeotropic anchoring sedimenting within nematic liquid crystal 4-cyano-4′-pentylbiphenyl (5CB) has been studied at low Ericksen number. The magnitude of the spheres’ velocity depends on the angle θ between the far-field nematic director and the gravitational force, indicating an anisotropic Stokes drag. When the director is oriented at an oblique angle to the gravitational force, the velocity also acquires a component normal to the force, demonstrating the existence of a lift force generated by the fluid. The magnitude and direction of the velocity as functions of θ quantitatively obey theoretically predicted forms.
ISSN:0743-7463
1520-5827
DOI:10.1021/la3050412