title: Geometry of intensive scalar dissipation events in turbulence.
abstract: The maxima of the scalar dissipation rate in turbulence appear in the form of sheets and correspond to the potentially most intensive scalar mixing events. Their cross section extension determines a locally varying diffusion scale of the mixing process and extends the classical Batchelor picture of one mean diffusion scale. The distribution of the local diffusion scales is analyzed for different Reynolds and Schmidt numbers with a fast multiscale technique applied to very high-resolution simulation data. The scales always take values across the whole Batchelor range and beyond. Furthermore, their distribution is traced back to the distribution of the contractive short-time Lyapunov exponent of the flow.
authors.affiliation: Department of Computer Science and Applied Mathematics, The Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Kushnir
authors.forename: Jörg
authors.initials: J
authors.lastname: Schumacher
authors.forename: Achi
authors.initials: A
authors.lastname: Brandt