Behaviour of Energetic Coherent Structures in Turbulent Pipe Flow at High Reynolds Number - Couverture souple

Hallol, Zeinab

 
9783736975019: Behaviour of Energetic Coherent Structures in Turbulent Pipe Flow at High Reynolds Number
Couverture souple
ISBN 10 : 3736975015 ISBN 13 : 9783736975019
Editeur : Cuvillier, 2021

Synopsis

This thesis presents a new applied temporal-spatial analysis using time-resolved PIV measurements to investigate coherent structures' co-exist towards pipe axis in fully developed turbulent pipe flow at high Reynolds numbers. The new method facilitates the detection of coherent structures directly through the new streamwise fluctuating velocity field plots. The detection was done without involving the common usable Taylor hypothesis compared to the recognised spectral analysis. For streamwise (u) and wall-normal (v) velocity components, this methodology identifies the shear layer signature created by the encounters of bursting events caused due to the intensive presence of coherent structures and their interaction in the near-wall region. Nevertheless, spectra and co-spectra, as well as proper orthogonal decomposition (POD) analyses, are also applied in this study to identify the contribution of both large (LSMs) and very-large-scale motions (VLSMs) to turbulent kinetic energy and Reynolds shear stress. The spectral analysis utilises high-speed PIV measurements to revisit other earlier studies done via a single hot-wire anemometer. In the present study, hot-wire measurements were conducted at a very high Reynolds number range exceeding one million equivalent to Re_tau= 19 000 with high spatial resolution. The obtained results indicate the dominance of VLSMs in the logarithmic and outer layers. However, the outputs are deduced from their higher contribution to total energy production in streamwise and wall-normal directions at high Reynolds numbers. Furthermore, new observation explored from the temporal-spatial plots stated that VLSMs could be created from the alignment of LSMs.

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Éditeur
Cuvillier
Date d'édition
2021
Langue
anglais
ISBN 10 
3736975015
ISBN 13 
9783736975019
Reliure
Broché
Nombre de pages
146
Coordonnées du fabricant
info@cuvillier.de
info@cuvillier.de

Nonnenstieg 8
Göttingen
37075
Allemagne