Strongly Localized Events in Laboratory Turbulent Flows

Tsinober, A.; Vaisburd, H.

doi:10.1007/978-94-011-0457-9_92

Cited by 1 publication

(3 citation statements)

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“…3 Which was conjectured by Siggia (1981). 4Subsequently, the alignment between to and 22 was observed both in DNS of NSE (Balachandar, 1992;She, 1991;Tsinober, 1992;Sofia et al, 1994;Meneguzzi, 1991, 1994 andothers) and inviscid (Brachet et al, 1992;Fernadez et al, 1995;Ohkitani, 1993;Ohkitani and Kishiba, 1995;Porter et al, 1994Porter et al, , 1995 as well experimentally (Kit et al, 1993;Lemonis et al, 1995;Tsinober et al, 1992Tsinober et al, , 1995. 5 In Tsinober et al, (1995b) we described briefly some results on our fourth question on the properties of the process of production of enstrophy generation and the role of the vorticity pressure Hessian interaction in this process.…”

Section: Introductory Notes and Motivationmentioning

confidence: 81%

“…On the other hand, both experiments (Tsinober et al, 1992;Tsinober et al, 1995) and computations (Vincent and Meneguzzi, 1994) show that the contribution to the total mean enstrophy generation (DiCOjsij = OO2•i COS2( to, 4i) ~ {7 = ~ o.i, o.e = (D2~ COS2( to, 4c~) (no summation over ~) from the term corresponding to the largest positive eigenvalue is of the same order (and even larger) than the one corresponding to the intermediate eigenvalue, i.e. o1-co221 cos2(to,41)>o'2 = to222 cos2 (to, 42 ).…”

Section: Introductory Notes and Motivationmentioning

confidence: 93%

“…However, this is true only of their means, whereas other properties of the surrogates and of the 'true' quantities (which are geometrical invariants independent of the frame of reference unlike the surrogates) are generally different (Gibson and Masiello, 1972;Tsinober, 1995). Their PDFs' are essentially different (Corrsin and Foumier, 1982;Hosokawa and Ode, 1996;Narasimha, 1990;Tsinober et al, 1992), their spectra are considerably different too (Brachet, 1991;Tsinober et al, 1992) and so are their fractal properties (Hosokawa and Ode, 1996;Tsinober and Vaisburd, 1995). • As mentioned above, it is a common argument that the prevalence of vortex stretching is due to the predominance of stretching of material lines, and that this argument is, at best, true in part only, since, there exist several qualitative differences between the two processes.…”

Section: Geometrical Statisticsmentioning

confidence: 99%

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A study of properties of vortex stretching and enstrophy generation in numerical and laboratory turbulence

Tsinober¹,

Shtilman

Vaisburd

1997

Fluid Dyn. Res.

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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 to and the eigenvectors of the rate of strain tensor 2i (especially -but not only -between to and 22) 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-tojsij. It is shown that the quasi-two-dimensional regions corresponding to large cos(to, 22) 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. * Corresponding author. 1A brief presentation of some results of this paper was published in Tsinober et al. (1995b).

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