title: Stochastic dynamics of particles trapped in turbulent flows.
abstract: The long-time dynamics of large particles trapped in two nonhomogeneous turbulent shear flows is studied experimentally. Both flows present a common feature, a shear region that separates two colliding circulations, but with different spatial symmetries and temporal behaviors. Because large particles are less and less sensitive to flow fluctuations as their size increases, we observe the emergence of a slow dynamics corresponding to back-and-forth motions between two attractors, and a super-slow regime synchronized with flow reversals when they exist. Such dynamics is substantially reproduced by a one-dimensional stochastic model of an overdamped particle trapped in a two-well potential, forced by a colored noise. An extended model is also proposed that reproduces observed dynamics and trapping without potential barrier: the key ingredient is the ratio between the time scales of the noise correlation and the particle dynamics. A total agreement with experiments requires the introduction of spatially nonhomogeneous fluctuations and a suited confinement strength.
authors.affiliation: Laboratoire de Physique, ENS de Lyon, UMR CNRS 5672, Université de Lyon, France.
authors.forename: N
authors.initials: N
authors.lastname: Machicoane
authors.affiliation: Departamento de Física y Matemática Aplicada, University of Navarra, P.O. Box 177, E-31080 Pamplona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: López-Caballero
authors.affiliation: Laboratoire de Physique, ENS de Lyon, UMR CNRS 5672, Université de Lyon, France.|Irstea, UR TERE, F-35044 Rennes, France.
authors.forename: L
authors.initials: L
authors.lastname: Fiabane
authors.affiliation: Laboratoire de Physique, ENS de Lyon, UMR CNRS 5672, Université de Lyon, France.
authors.forename: J-F
authors.initials: JF
authors.lastname: Pinton
authors.affiliation: Laboratoire de Physique, ENS de Lyon, UMR CNRS 5672, Université de Lyon, France.|Laboratoire des Écoulements Géophysiques et Industriels, CNRS/UJF/G-INP UMR 5519, Boîte Postale 53, F-38041 Grenoble, France.
authors.forename: M
authors.initials: M
authors.lastname: Bourgoin
authors.affiliation: Departamento de Física y Matemática Aplicada, University of Navarra, P.O. Box 177, E-31080 Pamplona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Burguete
authors.affiliation: Laboratoire de Physique, ENS de Lyon, UMR CNRS 5672, Université de Lyon, France.
authors.forename: R
authors.initials: R
authors.lastname: Volk
mesh_terms: D008962:Models, Theoretical; D009038:Motion; D011336:Probability; D033081:Shear Strength; D013269:Stochastic Processes