摘要：

Application of Large Eddies Break-Up (LEBU) devices is a well-known method to drag reduc-tion in turbulent boundary layers. Although the general idea of such devices is obvious, the com-prehensive explanation of their function remains uncertain. Therefore, LEBU design and optimiza-tion is a complicated problem. Present work attempts to clarify LEBU effect on turbulent boundary layer structure. The investigation is based on the newly developed 'deterministic turbulence method'. The idea of existence of the deterministic wall turbulence was advanced recently in [1, 2] based on experimental data and on the idea on the universality of the turbulence production mecha-nisms in transitional and turbulent wall shear flows [3]. This idea consists in the following. D e f i n i t i o n s . By the stochastic turbulence, we mean the turbulence, which microscopic structure (the instantaneous spatial velocity field of fluid particles) can not be reproduced repeatedly (although the average structure — can be reproduced). By the deterministic (causal) turbulence, we mean the flow, which microscopic structure can be reproduced repeatedly from one realization to another at reproduction of the same initial conditions for perturbations incoming into the boundary layer. A s s u m p t i o n s . There are some boundary layers in which laws of flow evolution are determi-nistic, while the stochastic properties result entirely from external perturbations amplified by vari-ous instabilities. We also assume that if all instabilities in these boundary layers are convective then weak stochastic external perturbations may not have enough time to be amplified. Under these as-sumptions the flow may remain deterministic even if it is turbulent. It was shown in [1, 2] that the deterministic (reproducible) turbulence actually exists in nature and can be generated experimentally in some boundary-layer flows. Besides important philosophi-cal meaning, this result provides investigators with a very powerful tool of subsequent turbulence research. An example of one of possible efficient application of this tool is presented below.

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