Proper orthogonal decomposition analysis and modelling of the wake deviation behind a squareback Ahmed body

Podvin, Bérengère; Pellerin, Stéphanie; Fraigneau, Yann; Evrard, Antoine; Cadot, Olivier

doi:10.1103/physrevfluids.5.064612

Cited by 25 publications

(41 citation statements)

References 32 publications

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“…Podvin et al. (2020) recently took advantage of the three-dimensional POD to correlate the different known global dynamics to the base suction (or base drag). They found that the larger the quasi-steady deviation of the wake, the larger the base drag, while large vortex shedding intensity was correlated to lower quasi-steady deviation and then to lower drag.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, an alternative low-dimensional modelling based on POD was obtained by Podvin et al. (2020) by projecting the Navier–Stokes equations on the most energetic POD modes. However, their POD basis did not contain switching events, as no switching occurred during the simulation.…”

Section: Introductionmentioning

confidence: 99%

“…The aim of the present paper is to pursue the modelling based on the POD of Podvin et al. (2020) but on a longer simulation that contains wake switchings. It will be shown that the POD basis is completed by a new POD mode associated with a switching event.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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 ( $Re$ ) 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.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…2014; Podvin et al. 2020), particularly advised for symmetry-breaking instabilities of flows around a symmetric configuration (Fabre, Auguste & Magnaudet 2008; Borońska & Tuckerman 2010). Since the fluidic pinball exhibits a mirror symmetry, we further investigate the force expression under the reflectional (Z2) symmetry.…”

Section: Introductionmentioning

confidence: 99%

“…The consistent form with Liang & Dong (2014) strengthens the theoretical basis of the force expression. Any known symmetric property of the modes is usually considered in the relative modal analysis (Rigas et al 2014;Podvin et al 2020), particularly advised for symmetry-breaking instabilities of flows around a symmetric configuration (Fabre, Auguste & Magnaudet 2008;Borońska & Tuckerman 2010). Since the fluidic pinball exhibits a mirror symmetry, we further investigate the force expression under the reflectional (Z2) symmetry.…”

Section: Introductionmentioning

confidence: 99%