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EXPERIMENTAL STUDY OF REPRODUCIBILITY OF INSTANTANEOUS STRUCTURE OF THE DETERMINISTIC WALL TURBULENCE

V.I. Borodulin
Institute of Theoretical and Applied Mechanics of Siberian Branch of the Russian Academy of Sciences, Institutskaya street 4/1, Novosibirsk, 630090, Russian Federation

Yury S. Kachanov
Institute of Theoretical and Applied Mechanics of Siberian Branch of the Russian Academy of Sciences, Institutskaya street 4/1, Novosibirsk, 630090, Russian Federation

Résumé

The recently introduced term of 'the deterministic turbulence' refers to the post-transitional boundary-layer flow, which looks like a turbulent one (according to a common viewpoint, thought that viewpoint is not well defined) but displays a noticeable degree of determinism. Such kind of turbulence may occur in boundary layers where transition is caused by instabilities of convective type. The experimental realization of deterministic turbulence has been demonstrated not long ago. The present work deals with analysis of flow structures obtained experimentally in the 2D boundary layer with moderately unfavourable pressure gradient. The vortical structures typical for the turbulent boundary layer were reproduced many times by means of precise reproduction of initial disturbances and maintenance of the mean flow characteristics. Downstream evolution of those typical structures and their increasing divergence within an ensemble of realizations, i.e. the degree of reproducibility of the deterministic turbulence has been documented and analyzed.