Time-dependent diffusion coefficients for chaotic advection due to fluctuations of convective rolls

Kazuma Yamanaka, Takayuki Narumi, Megumi Hashiguchi, Hirotaka Okabe, Kazuhiro Hara, Yoshiki Hidaka

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The properties of chaotic advection arising from defect turbulence, that is, weak turbulence in the electroconvection of nematic liquid crystals, were experimentally investigated. Defect turbulence is a phenomenon in which fluctuations of convective rolls arise and are globally disturbed while maintaining convective rolls locally. The time-dependent diffusion coefficient, as measured from the motion of a tagged particle driven by the turbulence, was used to clarify the dependence of the type of diffusion on coarse-graining time. The results showed that, as coarse-graining time increases, the type of diffusion changes from superdiffusion ? subdiffusion ? normal diffusion. The change in diffusive properties over the observed timescale reflects the coexistence of local order and global disorder in the defect turbulence.

Original languageEnglish
Article number99
JournalFluids
Volume3
Issue number4
DOIs
Publication statusPublished - Dec 2018

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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