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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 15:27:51 +0000Interactions between scales in wall turbulence: phase relationships, amplitude modulation and the importance of critical layers
https://resolver.caltech.edu/CaltechAUTHORS:20210312-151430797
Authors: {'items': [{'id': 'Jacobi-Ian', 'name': {'family': 'Jacobi', 'given': 'Ian'}, 'orcid': '0000-0001-7377-8292'}, {'id': 'Chung-Daniel', 'name': {'family': 'Chung', 'given': 'Daniel'}, 'orcid': '0000-0003-3732-364X'}, {'id': 'Duvvuri-Subrahmanyam', 'name': {'family': 'Duvvuri', 'given': 'Subrahmanyam'}, 'orcid': '0000-0001-8082-1658'}, {'id': 'McKeon-B-J', 'name': {'family': 'McKeon', 'given': 'Beverley J.'}, 'orcid': '0000-0003-4220-1583'}]}
Year: 2021
DOI: 10.1017/jfm.2020.770
We present a framework for predicting the interactions between motion at a single scale and the underlying stress fluctuations in wall turbulence, derived from approximations to the Navierâ€“Stokes equations. The dynamical equations for an isolated scale and stress fluctuations at the same scale are obtained from a decomposition of the governing equations and formulated in terms of a transfer function between them. This transfer function is closely related to the direct correlation coefficient of Duvvuri & McKeon (J. Fluid Mech., vol. 767, 2015, R4), and approximately to the amplitude modulation coefficient described in Mathis et al. (J. Fluid Mech., vol. 628, 2009, pp. 311â€“337), by consideration of interactions between triadically consistent scales. In light of the agreement between analysis and observations, the modelling approach is extended to make predictions concerning the relationship between very-large motions and small-scale stress in the logarithmic region of the mean velocity. Consistent with experiments, the model predicts that the zero-crossing height of the amplitude modulation statistic coincides with the wall-normal location of the very large-scale peak in the one-dimensional premultiplied spectrum of streamwise velocity fluctuations, the critical layer location for the very large-scale motion. Implications of fixed phase relationships between small-scale stresses and larger isolated scales for closure schemes are briefly discussed.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pawd6-2cg23