title: Stretching fields and mixing near the transition to nonperiodic two-dimensional flow.
abstract: Although time-periodic fluid flows sometimes produce mixing via Lagrangian chaos, the additional contribution to mixing caused by nonperiodicity has not been quantified experimentally. Here, we do so for a quasi-two-dimensional flow generated by electromagnetic forcing. Several distinct measures of mixing are found to vary continuously with the Reynolds number, with no evident change in magnitude or slope at the onset of nonperiodicity. Furthermore, the scaled probability distributions of the mean Lyapunov exponent have the same form in the periodic and nonperiodic flow states.
authors.affiliation: Condensed Matter & Thermal Physics Group and The Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Twardos
authors.forename: P E
authors.initials: PE
authors.lastname: Arratia
authors.forename: M K
authors.initials: MK
authors.lastname: Rivera
authors.forename: G A
authors.initials: GA
authors.lastname: Voth
authors.forename: J P
authors.initials: JP
authors.lastname: Gollub
authors.forename: R E
authors.initials: RE
authors.lastname: Ecke