title: Chaotic motion of light particles in an unsteady three-dimensional vortex: experiments and simulation.
abstract: We study the chaotic motion of a small rigid sphere, lighter than the fluid in a three-dimensional vortex of finite height. Based on the results of Eulerian and Lagrangian measurements, a sequence of models is set up. The time-independent model is a generalization of the Burgers vortex. In this case, there are two types of attractors for the particle: a fixed point on the vortex axis and a limit cycle around the vortex axis. Time dependence might combine these regular attractors into a single chaotic attractor, however its robustness is much weaker than what the experiments suggest. To construct an aperiodically time-dependent advection dynamics in a simple way, Gaussian noise is added to the particle velocity in the numerical simulation. With an appropriate choice of the noise properties, mimicking the effect of local turbulence, a reasonable agreement with the experimentally observed particle statistics is found.
authors.affiliation: Institute of Theoretical Physics, Eötvös Loránd University, Pázmány P. s. 1/A, H-1117 Budapest, Hungary and Department of Physics, Eszterházy Károly College, Eszterházy K. s. 1, H-3300 Eger, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Vanyó
authors.affiliation: von Kármán Laboratory for Environmental Flows, Eötvös Loránd University, Pázmány P. s. 1/A, H-1117 Budapest, Hungary and Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus-Senftenberg, Siemens-Halske Ring 14, D-03046 Cottbus, Germany.
authors.forename: Miklós
authors.initials: M
authors.lastname: Vincze
authors.affiliation: von Kármán Laboratory for Environmental Flows, Eötvös Loránd University, Pázmány P. s. 1/A, H-1117 Budapest, Hungary and Department of Physics of Complex Systems, Eötvös Loránd University, Pázmány P. s. 1/A, H-1117 Budapest, Hungary.
authors.forename: Imre M
authors.initials: IM
authors.lastname: Jánosi
authors.affiliation: Institute of Theoretical Physics, Eötvös Loránd University, Pázmány P. s. 1/A, H-1117 Budapest, Hungary and von Kármán Laboratory for Environmental Flows, Eötvös Loránd University, Pázmány P. s. 1/A, H-1117 Budapest, Hungary and MTA-ELTE Theoretical Physics Research Group, Pázmány P. s. 1/A, H-1117 Budapest, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Tél
mesh_terms: D009038:Motion; D017711:Nonlinear Dynamics; D013997:Time Factors