Title: A study of properties of vortex stretching and enstrophy generation in numerical and laboratory turbulence
Abstract: Dynamically relevant alignments are used in order to show that regions with weak vorticity are not structureless, non-Gaussian and dynamically not passive. for example, the structure of vorticity in quasi-homogeneous/isotropic turbulent flows is associated with strong alignment between vorticity ω and the eigenvectors of the rate of strain tensor λi (especially — but not only — between ω and λ2) rather than with intense vorticity only. Consequently, much larger regions of turbulent flow than just those with intense vorticity are spatially structured. The whole flow field — even with the weakest measurable enstrophy — is strongly non-Gaussian, which among other things is manifested in strong alignment between vorticity and the vortex stretching vector Wi ≡ ωjSij. It is shown that the quasi-two-dimensional regions corresponding to large cos(ω, λ2) are qualitatively different from purely two-dimensional ones, e.g. in that they possess essentially nonvanishing enstrophy generation, which is larger than its mean for the whole field.
Publication Year: 1997
Publication Date: 1997-12-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 52
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