Tumbling of long flexible fibers in isotropic turbulence
Phys. Rev. Fluids 11, 034301 – Published 11 March, 2026
DOI: https://doi.org/10.1103/d7xr-8bqk
Abstract
In this study, we experimentally investigate the rotational dynamics of flexible fibers in homogeneous and isotropic turbulence. Three high-speed cameras are used to determine and track the three-dimensional conformation of the fibers. The rotational dynamics is characterized here by both the rotation of the end-to-end vector and the rotation of the eigenframe of the deformed fibers. We observe an increase of the rotation rate when the flexibility of the fiber is increased. To model this increase, we propose a scaling law for the evolution of the mean curvature, which depends on the mechanical properties of the fiber and the properties of turbulence. This model extends the one proposed by C. Brouzet et al. [Phys. Rev. Fluids 6, 024601 (2021)] for relatively stiff fibers. The evolution of the curvature is then used to model the mean shape of a flexible fiber, which determines its rotation rate. Our model is in very good agreement with our experimental measurements as long as the mean conformation can be considered as planar—so for moderately flexible fibers.
