3 research outputs found
Eléments de bilan du programme quinquennal 1998-2002 et réflexions
D:2003/3543/18info:eu-repo/semantics/publishe
Direct numerical simulation and large-eddy simulation of wake vortices : going from laboratory conditions to flight conditions
This paper aims at presenting DNS and LES as applied to the simulation
of vortex wakes: in laboratory conditions (moderate to medium Reynolds numbers) and
up to real aircraft conditions (high to very high Reynolds numbers). Only incompressible
°ows are considered. DNS and LES are able to capture complex 3-D physics provided one
uses high quality numerical methods: methods with negligible numerical dissipation (i.e.,
methods that conserve energy in absence of viscosity and/or subgrid modelling) and with
low dispersion errors (to properly transport complex vortical structures). Methods that
can do that are: spectral methods, high order ¯nite di®erence methods, and vortex-in-cell
(VIC) methods. As the problems of interest are of large spatial extent and contain vortices
with small cores, it is also essential that the methods be e±ciently parallelized. As to LES
of wake vortex °ows, this require subgrid scale (SGS) models that are essentially inactive
during the gentle, well-resolved, phases of the °ow and within the vortex cores, and that
become active only during the complex turbulent phases of the °ow. The recent multiscale
models, that act solely on the high wavenumbers modes of the LES, are seen to be most
appropriate. We present some illustrative examples of DNS and LES results that were
obtained within our group