A unique experimental facility along with unique methods of measurement of vorticity, helicity and related quantities were used in order to obtain the following main results. Strong experimental evidence in favour of the existence of the phenomenon of spontaneous reflectional symmetry breaking (SRSB) in turbulent flows with initial and boundary conditions, which are nominally reflectionally symmetrical. In contrast to widespread expectation, this SRSB is exhibited not only in production of non-zero mean helicity, but in a number of more subtle effects related to spectrally and spatially localized SRSB. We observed qualitatively different cases of SRSB exhibited in large and small scales separately and concomitantly with helicity of different signs at different scales and, in particular, cases with SRSB and vanishing mean helicity. Finally, in some cases the flow was almost perfectly reflectionally symmetrical, possessing an almost vanishing cospectrum. A surprisingly strong variability of this phenomenon was observed in contrast with 'conventional' characteristics, which exhibited regular behaviour. On the basis of a large number of different results our conclusion is that the variability of parameters characterizing SRSB is an intrinsic property at least of some turbulent flows.
|Number of pages||19|
|Journal||Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences|
|State||Published - 8 Nov 2001|
- Spontaneous breaking of reflectional symmetry
- Turbulent flow