Year: 2026
Type: preprint
Abstract: Fiber suspensions are common in biological and environmental flows and are widely used in industrial applications. Fiber transport and orientation dynamics are affected by interactions with the surrounding fluid and strongly depend on the nature of the flow. The complexity of realistic flows, which are often heterogeneous or time-dependent, hinders a full understanding of fiber dynamics. In this study, we combine microfluidic experiments, theory and numerical simulations to investigate the orientation dynamics of rigid neutrally buoyant fibers in a well-controlled model system, a streamwise stationary vortex at moderate Reynolds number. Despite the three-dimensional nature of the flow, the orientation dynamics are remarkably simple: the fiber orientation is accurately described by Jeffery equations coupled with the Burgers-vortex model over a large range of particle Reynolds number. We show that fibers undergo uniform precession about the vortex axis driven by fluid vorticity while simultaneously aligning with the latter due to strain in the vortex core. These two motions are decoupled, with the alignment timescale determined by the local strain rate and the fiber aspect ratio. Finite particle size and inertia induce weak deviations from the base flow streamlines while leaving the orientational dynamics largely unaffected. These results establish a simple framework for understanding the behavior of elongated particles in stretched vortex flows, which constitute key building blocks of turbulence.
Source: arXiv (Cornell University)
Institutions: Physique et Mécanique des Milieux Hétérogènes, ESPCI Paris, Centre National de la Recherche Scientifique, École Polytechnique, Université Paris Cité, Sorbonne Université, Laboratoire d'Hydrodynamique de l'École polytechnique, Institut Polytechnique de Paris, Institut Universitaire de France
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
Funders: Ministère de l'Enseignement supérieur, de la Recherche et de l'Innovation, Agence Nationale de la Recherche, Ministère de l'Enseignement Supérieur et de la Recherche, Centre National de la Recherche Scientifique, Université de Recherche Paris Sciences et Lettres, Institut Pierre-Gilles de Gennes
OpenAlex ID: W7169565537