The non-equilibrium dissipation scaling in large Reynolds number turbulence generated by rectangular fractal grids
File(s)
Author(s)
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.
Date Issued
2021-05-28
Date Acceptance
2021-04-30
Citation
Physical Review Fluids, 2021, 6 (5)
ISSN
2469-990X
Publisher
American Physical Society
Journal / Book Title
Physical Review Fluids
Volume
6
Issue
5
Copyright Statement
©2021 American Physical Society.
Sponsor
Commission of the European Communities
Grant Number
FP7 - 317269
Subjects
Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
Physics
ENERGY
TEMPERATURE
REGION
DECAY
FLOW
0102 Applied Mathematics
0203 Classical Physics
0913 Mechanical Engineering
Publication Status
Published
Article Number
ARTN 054613