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Linear and non‐linear mechanisms in boundary layer turbulence
Author(s) -
Landahl Marten T.
Publication year - 1988
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.1650081006
Subject(s) - turbulence , boundary layer , amplitude , mechanics , physics , linearity , mathematics , classical mechanics , mathematical analysis , statistical physics , optics , quantum mechanics
The different stages of bursting and evolution of the fluctuation field in a turbulent boundary layer are governed by mechanisms that may be identified as either predominantly linear, i.e. governed by linear interaction with the mean shear flow, or non‐linear, i.e. with interaction between the fluctuation components also being important. Wave number‐frequency spectra reveal the presence of damped wave modes that may be modelled from the Orr‐Sommerfeld equation. Conditional sampled experimental data for streamwise velocity fluctuations in the wall layer obtained using the variable interval time averaging (VITA) method scale with the threshold level in a manner consistent with linearity. High‐amplitude wall pressure peaks show an approximately linear relationship with the associated vertical velocity fluctuations. Non‐linearity acts primarily in the near‐wall region where the fluctuation velocity is relatively the highest.