Low-order modelling of the wake dynamics of an Ahmed body

Podvin, Berengere, Pellerin, Stephanie, Fraigneau, Yann, Bonnavion, Guillaume and Cadot, Olivier ORCID: 0000-0001-7323-6418 (2021) Low-order modelling of the wake dynamics of an Ahmed body. JOURNAL OF FLUID MECHANICS, 927. r6-.

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Official URL: http://dx.doi.org/10.1017/jfm.2021.788

Abstract

<jats:p>We investigate the large-scale signature of the random switches between two mirrored turbulent wake states of flat-backed bodies. A direct numerical simulation (DNS) of the flow around an Ahmed body at a Reynolds number (<jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0022112021007886_inline1.png" /> <jats:tex-math>$Re$</jats:tex-math> </jats:alternatives> </jats:inline-formula>) of 10 000 is considered. Using proper orthogonal decomposition (POD), we identify the most energetic modes of the velocity field and build a low-dimensional model based on the first six fluctuating velocity modes capturing the characteristics of the flow dynamics during and between switches. In the absence of noise, the model produces random switches with characteristic time scales in agreement with the simulation and experiments. This chaotic model suggests that random switches are triggered by the increase of the vortex shedding activity. However, the addition of noise results in a better agreement in the temporal spectra of the coefficients between the model and the simulation.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	low-dimensional models, wakes
Divisions:	Faculty of Science and Engineering > School of Engineering
Depositing User:	Symplectic Admin
Date Deposited:	10 Feb 2022 10:01
Last Modified:	15 Mar 2024 14:05
DOI:	10.1017/jfm.2021.788
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3148609