Clear water scour around a finite array of cylinders

Oral Yagci*, Isilsu Yildirim, Mehmet Furkan Celik, Vasileios Kitsikoudis, Zaide Duran, V. S.Ozgur Kirca

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

This experimental study presents clear-water scour and deposition patterns around hexagonal arrays of circular cylinders in steady flow conditions. Understanding the scour processes around such configurations could facilitate the design of several hydraulic and marine engineering structures, such as bridge piers and piles. The flow alteration caused by the examined porous obstacles depends on the solid volume fraction of the obstacles and on the angle of attack of the incoming flow, due to the limited number of cylinders constituting the array. Flume experiments with erodible bed were carried out for four array densities (solid volume fractions: 0.14, 0.20, 0.32 and 0.56) under three different orientations (regular, angled and staggered configurations). The scour/deposition characteristics were obtained by means of laser scanner and the results were compared to solid cylinders of equal circumambient diameter. Different angles of attack of the incoming flow lead to different blockage ratios, which have direct impact on the scour characteristics and deposition patterns. The arrays with the higher solid volume fraction generated scour/deposition patterns similar to solid cylinder, while in the arrays with the lower solid volume fractions, local scour around the individual small cylinders became evident. Finally, considering that the load bearing capacity of a pier basically depends on the area of its cross-section, a comparison of the maximum induced scour depth and volume by the cylinder arrays and the solid cylinder with equal solid cross-sectional area is presented, in order to introduce an alternative pier configuration that induces less scour. The results showed that the array of cylinders could generate 27% less scour volume and 22% less scour depth compared to its single solid cylinder counterpart.

Original languageEnglish
Pages (from-to)114-129
Number of pages16
JournalApplied Ocean Research
Volume68
DOIs
Publication statusPublished - Oct 2017

Bibliographical note

Publisher Copyright:
© 2017 Elsevier Ltd

Funding

This study was carried out with the support of the Scientific Research Funding Program of Istanbul Technical University (ITU-BAP Program, Project Number: 39544). Vasileios Kitsikoudis acknowledges the financial support for post-doctoral research in Istanbul Technical University provided by The Scientific and Technological Research Council of Turkey (TUBITAK) under the Fellowship Program 2216 (Ref. No. 21514107-115.02-45898) for the first part of the study and the Post-Doctoral Research Funding by ITU for the last part of the study. The authors are grateful to ITU Hydraulics Laboratory technicians Hasan Yalcin, Mevlut Ulucinar and Yasar Aktas.

FundersFunder number
ITU-BAP39544
TUBITAK21514107-115.02-45898
International Technological University
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu
Istanbul Teknik Üniversitesi

    Keywords

    • Bridge pier
    • Clear-water scour
    • Cylinder array
    • Laser scanner
    • Pile
    • Scour at marine structures
    • Seabed-structure interaction

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