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Updated: Jul 26, 2025

The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
Shape- and orientation-dependent diffusiophoresis of colloidal ellipsoids
Viet Sang Doan1, Dong-Ook Kim2, Craig Snoeyink1
1Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA.
Abstract:
We present the diffusiophoresis of ellipsoidal particles induced by ionic solute gradients. Contrary to the common expectation that diffusiophoresis is shape independent, here we show experimentally that this assumption breaks down when the thin Debye layer approximation is relaxed. By tracking the translation and rotation of various ellipsoids, we find that the phoretic mobility of ellipsoids is sensitive to the eccentricity and the orientation of the ellipsoid relative to the imposed solute gradient, and can further lead to nonmonotonic behavior under strong confinement. We show that such a shape- and orientation-dependent diffusiophoresis of colloidal ellipsoids can be easily captured by modifying theories for spheres.
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