NONEQUILIBRIUM AND CLASSICAL DISSIPATION SCALINGS IN DNS OF HOMOGENEOUS ISOTROPIC DECAYING TURBULENCE etc15 Tracking Number 223Presentation: Session: Intermittency and scaling 2 Room: Room G Session start: 15:00 Tue 25 Aug 2015 Carlos B. da Silva carlos.silva@ist.utl.pt Affifliation: Instituto Superior Técnico, University of Lisbon Ryo Onishi onishi.ryo@jamstec.go.jp Affifliation: Center for Earth Information Science and Technology, Japan Agency for Marine-Earth Science and Technology Pedro C. Valente pedro.valente@ist.utl.pt Affifliation: Instituto Superior Técnico, University of Lisbon Topics: - Intermittency and scaling Abstract: We present data from direct numerical simulations of homogeneous isotropic decaying turbulence showing both the non-equilibrium and the classical dissipation scalings reported in wind-tunnel experiments of both regular and fractal grid-generated turbulence, i.e. Cε ∼ (Re0/Reλ)n with n of order unity and Cε ∼ constant, respectively (Re0 and Reλ are global and local Reynolds numbers). These two dissipation behaviours lead to different power-law decay exponents in both regimes also in accord with the experiments. Finally, we show that in both regimes the maximum non-linear energy cascade flux, Π, reasonably satisfies the classical expectation that Π ∼ K3/2/l. |