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The non-equilibrium dissipation scaling in large Reynolds number turbulence generated by rectangular fractal grids

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Zheng, Bruce, et al. (2021) - Rectangular fractal grid PRF.pdfAccepted version2.16 MBAdobe PDFView/Open
Title: The non-equilibrium dissipation scaling in large Reynolds number turbulence generated by rectangular fractal grids
Authors: Zheng, S
Bruce, P
Cuvier, C
Foucaut, J-M
Graham, J
Vassilicos, C
Item Type: Journal Article
Abstract: In this paper, the turbulence fields generated by a group of modified fractal grids, referred to as the rectangular fractal grids (RFGs), are documented and discussed. The experiments were carried out using hot-wire anemometry in three facilities at Imperial College London and the Laboratory of Fluid Mechanics in Lille, France. Due to the large Reynolds number of the resulting turbulence, several data processing methods for turbulence properties are carefully evaluated. Two spectral models were adopted, respectively, to correct the large and small wave-number ranges of the measured spectrum. After the technical discussion, the measurement results are presented in terms of one-point statistics, length scales, homogeneity, isotropy, and dissipation. The main conclusions are twofold. First, the location of maximum turbulence intensity xpeak is shown to be independent of the inlet Reynolds number but dependent on the ratio between the lengths of the largest grid bars in the transverse and vertical directions. This is crucial to the production of prescribed features of turbulent flows in laboratory. Second, these RFG-generated turbulent flows are shown to be quasihomogeneous in the decay region for x/xpeak>1.5, but the isotropy is poorer than that of the previous studied fractal square grid-generated turbulence. In the beginning of the decay region, a decreasing pattern of the integral length scale Lu and Taylor microscale λ was observed, yet the ratio Lu/λ remained roughly constant along the centerline, so Cε∼Re−1λ, complying with the nonequilibrium scaling relation reported in previous studies for various turbulent flows.
Issue Date: 28-May-2021
Date of Acceptance: 30-Apr-2021
URI: http://hdl.handle.net/10044/1/89714
DOI: 10.1103/PhysRevFluids.6.054613
ISSN: 2469-990X
Publisher: American Physical Society
Journal / Book Title: Physical Review Fluids
Volume: 6
Issue: 5
Copyright Statement: ©2021 American Physical Society.
Sponsor/Funder: Commission of the European Communities
Funder's Grant Number: FP7 - 317269
Keywords: Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
0102 Applied Mathematics
0203 Classical Physics
0913 Mechanical Engineering
Publication Status: Published
Article Number: ARTN 054613
Appears in Collections:Aeronautics