Complex spectral properties of non-Hermitian operators: An application to open-flow mixing systems

Research output: Contribution to journalArticle


We study the spectral properties of the advection-diffusion operator associated with a non-chaotic 3d Stokes flow defined in the annular region between counter-rotating cylinders of finite length. The focus is on the dependence of the eigenvalue-eigenfunction spectrum on the Peclet number Pe. Several convection-enhanced mixing regimes are identified, each characterized by a power law scaling, -μd∼Pe (γd, vs.Pe. Among these regimes, a Pe-independent scaling -μd=const (i.e., γ=0), qualitatively similar to the asymptotic regime of globally chaotic flows, is observed. This regime arises as the consequence of different eigenvalues branches interchanging dominance at increasing Pe. A combination of perturbation analysis and functional-theoretical arguments is used to explain the occurrence and the range of existence of each regime.


  • M. Giona
  • S. Cerbelli
  • F. Garofalo
External organisations
  • Sapienza University of Rome
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Sciences
Original languageEnglish
Article number34001
JournalEurophysics Letters
Issue number3
Publication statusPublished - 2008 Aug 1
Publication categoryResearch
Externally publishedYes