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Causal analysis of self-sustaining processes in the logarithmic layer of wall-bounded turbulence

Bae, H. J. and Encinar, M. P. and Lozano-Durán, A. (2018) Causal analysis of self-sustaining processes in the logarithmic layer of wall-bounded turbulence. Journal of Physics Conference Series, 1001 . Art. No. 012013. ISSN 1742-6588. PMCID PMC6800676. doi:10.1088/1742-6596/1001/1/012013.

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Despite the large amount of information provided by direct numerical simulations of turbulent flows, their underlying dynamics remain elusive even in the most simple and canonical configurations. Most common approaches to investigate the turbulence phenomena do not provide a clear causal inference between events, which is essential to determine the dynamics of self-sustaining processes. In the present work, we examine the causal interactions between streaks, rolls and mean shear in the logarithmic layer of a minimal turbulent channel flow. Causality between structures is assessed in a non-intrusive manner by transfer entropy, i.e., how much the uncertainty of one structure is reduced by knowing the past states of the others. We choose to represent streaks by the first Fourier modes of the streamwise velocity, while rolls are defined by the wall-normal and spanwise velocity modes. The results show that the process is mainly unidirectional rather than cyclic, and that the log-layer motions are sustained by extracting energy from the mean shear which controls the dynamics and time-scales. The well-known lift-up effect is also identified, but shown to be of secondary importance in the causal network between shear, streaks and rolls.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bae, H. J.0000-0001-6789-6209
Encinar, M. P.0000-0002-3007-5981
Lozano-Durán, A.0000-0001-9306-0261
Additional Information:© 2018 Published under licence by IOP Publishing Ltd. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Accepted papers received: 23 March 2018; Published online: 12 April 2018. This work was funded in part by the Coturb program of the European Research Council. H.J.B. and A.L.D. acknowledge the support of the Center for Turbulence Research and the NASA Transformative Aeronautics Concepts Program (grant no. NNX15AU93A). We also thank Prof. P. J. Ioannou for his helpful comments on the manuscript.
Funding AgencyGrant Number
European Research Council (ERC)UNSPECIFIED
Stanford UniversityUNSPECIFIED
PubMed Central ID:PMC6800676
Record Number:CaltechAUTHORS:20210315-145613612
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Official Citation:H. J. Bae et al 2018 J. Phys.: Conf. Ser. 1001 012013
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108439
Deposited By: Tony Diaz
Deposited On:19 Mar 2021 21:16
Last Modified:12 Jul 2022 19:49

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