Random sweeping effect in isotropic numerical turbulence

Sanada, Tsutomu; Shanmugasundaram, V.

doi:10.1063/1.858242

Cited by 45 publications

(47 citation statements)

References 11 publications

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“…The former is related to the local interaction of modes in Fourier space, i.e., of eddies of similar sizes, while the latter deals with the non-local interaction in Fourier space resulting from the advection of small eddies by the energy containing ones. It has been theorised [49,50] and later shown [51,52] that the temporal decorrelation of Fourier modes of the Eulerian velocity field in homogeneous and isotropic turbulence is determined by this sweeping. In numerical simulations sweeping is often quantified by computing the decorrelation time of individual Fourier modes, using two-time correlation functions.…”

Section: Homogeneous and Isotropic Turbulencementioning

confidence: 99%

The spatio-temporal spectrum of turbulent flows

2015

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Abstract. Identification and extraction of vortical structures and of waves in a disorganised flow is a mayor challenge in the study of turbulence. We present a study of the spatio-temporal behavior of turbulent flows in the presence of different restitutive forces. We show how to compute and analyse the spatio-temporal spectrum from data stemming from numerical simulations and from laboratory experiments. Four cases are considered: homogeneous and isotropic turbulence, rotating turbulence, stratified turbulence, and water wave turbulence. For homogeneous and isotropic turbulence, the spectrum allows identification of sweeping by the large scale flow. For rotating and for stratified turbulence, the spectrum allows identification of the waves, precise quantification of the energy in the waves and in the turbulent eddies, and identification of physical mechanisms such as Doppler shift and wave absorption in critical layers. Finally, in water wave turbulence the spectrum shows a transition from gravity-capillary waves to bound waves as the amplitude of the forcing is increased.

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Section: Homogeneous and Isotropic Turbulencementioning

confidence: 99%

The spatio-temporal spectrum of turbulent flows

2015

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“…[3][4][5][6][7] Total or Lagrangian accelerations are comparatively small and obey Kolmogorov scaling. The dominance of the mean square values of convective and local accelerations is confirmed by DNS results of stationary isotropic turbulence.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] Work is inspired by the wish to extend understanding of the statistical structure of turbulence. A specific motivation is the relevance of these parameters for Lagrangian models of turbulence: e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

Eulerian short-time statistics of turbulent flow at large Reynolds number

Brouwers

2004

Physics of Fluids

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An asymptotic analysis is presented of the short-time behavior of second-order temporal velocity structure functions and Eulerian acceleration correlations in a frame that moves with the local mean velocity of the turbulent flow field. Expressions in closed-form are derived which cover the viscous and inertial subranges. They apply to general anisotropic turbulence at a large Reynolds number obeying the Kolmogorov theory. Previously published results for isotropic turbulence emerge as special cases. In the derivation use is made of the approximation of temporarily frozen turbulence proposed by Tennekes. It is shown to be valid under conditions not other than those for which the Kolmogorov hypotheses hold. The effects of intermittency appear to be marginal.

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“…The random sweeping hypothesis proposes a temporal decorrelation process in incompressible isotropic turbulence and a simple model for space-time correlations of velocity fluctuations [1]. These results are examined theoretically [3][4][5] and verified experimentally [6] and numerically [7,8]. The space-time correlation models are used to predict the scalings of wave number or frequency energy spectra in turbulent flows [9][10][11][12].…”

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confidence: 99%

“…The swept-wave model is further extended to account for a constant mean velocity. [7,8]. The space-time correlation models are used to predict the scalings of wave number or frequency energy spectra in turbulent flows [9][10][11][12].…”

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confidence: 99%

Temporal decorrelations in compressible isotropic turbulence

Zhang

2013

Phys. Rev. E

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Temporal decorrelations in compressible isotropic turbulence are studied using the space-time correlation theory and direct numerical simulation. A swept-wave model is developed for dilatational components, while the classic random sweeping model is proposed for solenoidal components. The swept-wave model shows that the temporal decorrelations in dilatational fluctuations are dominated by two physical processes: random sweeping and wave propagation. These models are supported by the direct numerical simulation of compressible isotropic turbulence, in the sense that all curves of normalized time correlations for different wave numbers collapse into a single one using the normalized time separations. The swept-wave model is further extended to account for a constant mean velocity. [7,8]. The space-time correlation models are used to predict the scalings of wave number or frequency energy spectra in turbulent flows [9][10][11][12]. The decorrelation processes are also relevant to the non-Gaussian statistics [13] and intermittency [14]. Their further applications can be found in turbulence generated noise [15]. The recently increasing studies on compressible isotropic turbulence raise such a question on the effects of compressibility on decorrelation processes [16][17][18]. In this Rapid Communication, we will study the decorrelation processes in compressible isotropic turbulence and propose a model for space-time correlations of dilatational components.A compressible turbulence is associated with two characteristic velocities: fluid velocity and sound speed, whereas an incompressible one is only associated with fluid velocity. Therefore, the decorrelation processes in compressible turbulence are very different from the incompressible one. A space-time correlation is the essential quantity to measure the decorrelation processes in turbulent flows. Three typical models exist for space-time correlations in turbulence theory. The first one is, as stated above, the random sweeping model for incompressible turbulence [1]. We will show that it cannot characterize the dilatational components in compressible turbulence. The second one is the Taylor frozen flow model [19]. It has been shown that this model is not a good approximation for dilatational components [20]. The third one is the linear wave propagation model [20]. This model has been used for dilatational components when compressible turbulence has a dominating mean velocity. However, it does not decrease with increasing temporal separation, which violates the nature of correlation functions.In this Rapid Communication, we will develop a space-time correlation model for compressible isotropic turbulence. This * hgw@lnm.imech.ac.cn is achieved by the Helmholtz decomposition: a velocity field can be split into the solenoidal and dilatational components. A swept-wave model will be developed for the dilatational components, while the solenoidal components are expected to follow the random sweeping model. The swept-wave model will be numerically validated and further us...

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Random sweeping effect in isotropic numerical turbulence

Cited by 45 publications

References 11 publications

The spatio-temporal spectrum of turbulent flows

The spatio-temporal spectrum of turbulent flows

Eulerian short-time statistics of turbulent flow at large Reynolds number

Temporal decorrelations in compressible isotropic turbulence

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