Generalised quasilinear approximations in homogeneous shear turbulence
File(s)
Published version
Author(s)
Luo, Zhenghao
Gonzalez Hernandez, Carlos
Hwang, Yongyun
Type
Journal Article
Abstract
A generalized quasilinear (GQL) approximation (Marston , , vol. 116, 2016, 104502) is applied to homogeneous shear turbulence following a previous work on the quasilinear (QL) model (Hernndez & Hwang, , vol. 904, 2020, A11). For the GQL approximation, the velocity fluctuations are decomposed into low- and high-wavenumber groups, the former of which is solved by considering the full nonlinear equations whereas the latter is obtained from the linearised equations around the former. Unlike the QL model, which typically shows significant inhibition of the energy cascade in the direction along which the linearisation is made, the GQL model shows an energy cascade that is more active than the QL model} because more Fourier modes included in the low-wavenumber group allow for an extra energy transfer mechanism from the low- to high-wavenumber group via the so-called `scattering’ mechanism. It is shown that this scattering mechanism is most active when a relatively small and suitable number of Fourier modes are included in the low-wavenumber group instead of a large number of the Fourier modes being so, and this is explained in terms of the neutral Lyapunov vector forming the solution to the linear equations for the high-wavenumber group. As a consequence, the turbulence statics from the GQL model with a relatively small number of the Fourier modes in the low-wavenumber group are closer to those from DNS than those from the model with a large number of the Fourier modes in the low-wavenumber group. Finally, the QL/GQL approximations made in the streamwise and spanwise directions are compared, with emphasis on the role of slow pressure and the related pressure strain transport.
Date Issued
2023-06
Date Acceptance
2023-04-21
Citation
Physical Review Fluids, 2023, 8 (6), pp.1-26
ISSN
2469-990X
Publisher
American Physical Society
Start Page
1
End Page
26
Journal / Book Title
Physical Review Fluids
Volume
8
Issue
6
Copyright Statement
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0
International license. Further distribution of this work must maintain attribution to the author(s) and the
published article’s title, journal citation, and DOI.
International license. Further distribution of this work must maintain attribution to the author(s) and the
published article’s title, journal citation, and DOI.
License URL
Identifier
https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.064604
Publication Status
Published
Article Number
064604
Date Publish Online
2023-06-07