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Subgrid-scale stresses and scalar fluxes constructed by the multi-scale turnover Lagrangian map

Subgrid-scale stresses and scalar fluxes constructed by the multi-scale turnover Lagrangian map
Subgrid-scale stresses and scalar fluxes constructed by the multi-scale turnover Lagrangian map
The multi-scale turnover Lagrangian map (MTLM) [C. Rosales and C. Meneveau, “Anomalous scaling and intermittency in three-dimensional synthetic turbulence,” Phys. Rev. E 78, 016313 (2008)] uses nested multi-scale Lagrangian advection of fluid particles to distort a Gaussian velocity field and, as a result, generate non-Gaussian synthetic velocity fields. Passive scalar fields can be generated with the procedure when the fluid particles carry a scalar property [C. Rosales, “Synthetic three-dimensional turbulent passive scalar fields via the minimal Lagrangian map,” Phys. Fluids 23, 075106 (2011)]. The synthetic fields have been shown to possess highly realistic statistics characterizing small scale intermittency, geometrical structures, and vortex dynamics. In this paper, we present a study of the synthetic fields using the filtering approach. This approach, which has not been pursued so far, provides insights on the potential applications of the synthetic fields in large eddy simulations and subgrid-scale (SGS) modelling. The MTLM method is first generalized to model scalar fields produced by an imposed linear mean profile. We then calculate the subgrid-scale stress, SGS scalar flux, SGS scalar variance, as well as related quantities from the synthetic fields. Comparison with direct numerical simulations (DNSs) shows that the synthetic fields reproduce the probability distributions of the SGS energy and scalar dissipation rather well. Related geometrical statistics also display close agreement with DNS results. The synthetic fields slightly under-estimate the mean SGS energy dissipation and slightly over-predict the mean SGS scalar variance dissipation. In general, the synthetic fields tend to slightly under-estimate the probability of large fluctuations for most quantities we have examined. Small scale anisotropy in the scalar field originated from the imposed mean gradient is captured. The sensitivity of the synthetic fields on the input spectra is assessed by using truncated spectra or model spectra as the input. Analyses show that most of the SGS statistics agree well with those from MTLM fields with DNS spectra as the input. For the mean SGS energy dissipation, some significant deviation is observed. However, it is shown that the deviation can be parametrized by the input energy spectrum, which demonstrates the robustness of the MTLM procedure.
Subgrid-scale stresses, scalar uxes, multi-scale turnover Lagrangian map, synthetic turbulence generation
1070-6631
AL-Bairmani, Sukaina
9b14e3cc-1875-419d-8c3b-155cf9c073a5
Li, Yi
a64f2b8d-4985-4cd3-a35f-7fb53b33b193
Rosales, Carlos
f2d419c1-a66b-41c7-99c2-28b84f234615
Xie, Zhengtong
98ced75d-5617-4c2d-b20f-7038c54f4ff0
AL-Bairmani, Sukaina, Li, Yi, Rosales, Carlos and Xie, Zhengtong (2017) Subgrid-scale stresses and scalar fluxes constructed by the multi-scale turnover Lagrangian map Physics of Fluids, 29, (4)

AL-Bairmani, Sukaina, Li, Yi, Rosales, Carlos and Xie, Zhengtong (2017) Subgrid-scale stresses and scalar fluxes constructed by the multi-scale turnover Lagrangian map Physics of Fluids, 29, (4)

Record type: Article

Abstract

The multi-scale turnover Lagrangian map (MTLM) [C. Rosales and C. Meneveau, “Anomalous scaling and intermittency in three-dimensional synthetic turbulence,” Phys. Rev. E 78, 016313 (2008)] uses nested multi-scale Lagrangian advection of fluid particles to distort a Gaussian velocity field and, as a result, generate non-Gaussian synthetic velocity fields. Passive scalar fields can be generated with the procedure when the fluid particles carry a scalar property [C. Rosales, “Synthetic three-dimensional turbulent passive scalar fields via the minimal Lagrangian map,” Phys. Fluids 23, 075106 (2011)]. The synthetic fields have been shown to possess highly realistic statistics characterizing small scale intermittency, geometrical structures, and vortex dynamics. In this paper, we present a study of the synthetic fields using the filtering approach. This approach, which has not been pursued so far, provides insights on the potential applications of the synthetic fields in large eddy simulations and subgrid-scale (SGS) modelling. The MTLM method is first generalized to model scalar fields produced by an imposed linear mean profile. We then calculate the subgrid-scale stress, SGS scalar flux, SGS scalar variance, as well as related quantities from the synthetic fields. Comparison with direct numerical simulations (DNSs) shows that the synthetic fields reproduce the probability distributions of the SGS energy and scalar dissipation rather well. Related geometrical statistics also display close agreement with DNS results. The synthetic fields slightly under-estimate the mean SGS energy dissipation and slightly over-predict the mean SGS scalar variance dissipation. In general, the synthetic fields tend to slightly under-estimate the probability of large fluctuations for most quantities we have examined. Small scale anisotropy in the scalar field originated from the imposed mean gradient is captured. The sensitivity of the synthetic fields on the input spectra is assessed by using truncated spectra or model spectra as the input. Analyses show that most of the SGS statistics agree well with those from MTLM fields with DNS spectra as the input. For the mean SGS energy dissipation, some significant deviation is observed. However, it is shown that the deviation can be parametrized by the input energy spectrum, which demonstrates the robustness of the MTLM procedure.

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Accepted/In Press date: 22 March 2017
Published date: 10 April 2017
Keywords: Subgrid-scale stresses, scalar uxes, multi-scale turnover Lagrangian map, synthetic turbulence generation
Organisations: Aerodynamics & Flight Mechanics Group

Identifiers

Local EPrints ID: 407732
URI: http://eprints.soton.ac.uk/id/eprint/407732
ISSN: 1070-6631
PURE UUID: ff2daffb-be30-48b8-9d92-1ee8a79aa8b5
ORCID for Zhengtong Xie: ORCID iD orcid.org/0000-0002-8119-7532

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Date deposited: 25 Apr 2017 01:03
Last modified: 29 Sep 2017 19:03

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Contributors

Author: Sukaina AL-Bairmani
Author: Yi Li
Author: Carlos Rosales
Author: Zhengtong Xie ORCID iD

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