Evolution of turbulence and in-plane vortices in the near field flow behind multi-scale planar grids

Gan, L.; Krogstad, P.-Å

doi:10.1063/1.4960025

Evolution of turbulence and in-plane vortices in the near field flow behind multi-scale planar grids

Gan, L.; Krogstad, P.-Å

Authors

Dr Lian Gan lian.gan@durham.ac.uk
Associate Professor

P.-Å Krogstad

Abstract

In this experimental work, we carry out detailed two-dimensional particle image velocimetry investigations for the near field wakes behind a conventional and two multi-scale planar grids, using stitched camera fields of view. Statistical independent measurements are conducted focusing on the first few mesh distances downstream of the grid. It is found that the multiple integral length scales originated from the grids loose their importance on the turbulence development after about three mesh distances downstream, much earlier than the distance where the turbulence becomes homogeneous. The largest eddy size, represented by the integral length scales, does not show clear differences in its growth rate among the three grids after an initial development of three times the largest grid size downstream. Nevertheless, when examining individual vortex behaviours using conditional averaging and filtering processes, clear differences are found. The grids are found to have different decay rates of peak vorticity and projected vortex strengths. Despite these differences, the in-plane vorticity correlation function reveals that the mean vortex shape of all the grids shows a universal near-Gaussian pattern which does not change much as the turbulence decays.

Citation

Gan, L., & Krogstad, P. (2016). Evolution of turbulence and in-plane vortices in the near field flow behind multi-scale planar grids. Physics of Fluids, 28(8), Article 085101. https://doi.org/10.1063/1.4960025

Journal Article Type	Article
Acceptance Date	Jul 18, 2016
Online Publication Date	Aug 8, 2016
Publication Date	Aug 8, 2016
Deposit Date	Aug 2, 2016
Publicly Available Date	Oct 6, 2016
Journal	Physics of Fluids
Print ISSN	1070-6631
Electronic ISSN	1089-7666
Publisher	American Institute of Physics
Peer Reviewed	Peer Reviewed
Volume	28
Issue	8
Article Number	085101
DOI	https://doi.org/10.1063/1.4960025

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Copyright Statement
© 2016 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Gan, L. & Krogstad, P.-Å. (2016). Evolution of turbulence and in-plane vortices in the near field flow behind multi-scale planar grids. Physics of Fluids 28(8): 085101 and may be found at https://doi.org/10.1063/1.4960025