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ISSN オンライン: 2642-0554

AMPLITUDE AND FREQUENCY MODULATION OF THE SMALL SCALES IN A TURBULENT JET

D. Fiscaletti
Lab. for Aero & Hydrodynamics Department of Mechanical Engineering Delft University of Technology Leeghwaterstraat 21 2628 CA Delft, The Netherlands

Gerrit E. Elsinga
Laboratory for Aero and Hydrodynamics Delft University of Technology Leeghwaterstraat 21, 2628CA Delft, The Netherlands

Bharathram Ganapathisubramani
Engineering and the Environment University of Southampton Tizard, Highfield, Southampton, SO17 1BJ, UK

Jerry Westerweel
Laboratory for Aero- and Hydrodynamics, Delft University of Technology, Leeghwaterstraat 21, 2628 CA Delft, The Netherlands

要約

This work involves the large-scale amplitude and frequency modulation of the small-scale motions in fully-developed turbulence of a high Reynolds number jet. The scales responsible for the production of turbulent kinetic energy (large scales), and those responsible for its viscous dissipation (small scales) are extracted from time series of hot-wire signals, using a band-pass spectral filter. The top-down interaction between the turbulent scales is then examined. We show that the strength of the large-scale fluctuations affect non-linearly the amplitude of the small-scale signal. Furthermore, the higher frequency components within the small-scale signal exhibit stronger amplitude modulation, which evidences frequency modulation. Analogies and dissimilarities with turbulent flows other than jets are discussed.