Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical investigation of flow through and around a square array of cylinders
Hanbin Yang1,2,3,4, Xiandao Feng1,2,3,4, Hongxing Lin1,2,3,4
1CCCC Second Harbor Engineering Company LTD, Wuhan, China;
2Key Laboratory of Large-span Bridge Construction Technology, Wuhan, China;
3Research and Development Center of Transport Industry of Intelligent Manufacturing Technologies of Transport Infrastructure, Wuhan, China;
4CCCC Highway Bridge National Engineering Research Centre Co. Ltd, Wuhan, China

numerical studies on the subject have been conducted by Breuer (2000),
Travin et al. (2000), Catalano et al. (2003), Pattenden et al. (2005), Liangand Papadakis (2007), Grigoriadis et al. (2010), Lysenko et al. (2013),
Perković et al. (2013). The relationship between the drag coefficient andReynolds number, and the flow field characteristics under different
Reynolds numbers are the main foci in the above studies.

ABSTRACTThis paper investigates the flow through and around a square array ofcylinders. The investigations were performed numerically by RANS
simulation with kω-SST turbulent model using OpenFoam. Theeffects of volume fraction on the drag coefficient have not been studiedcompletely yet. The Reynolds numbers is Red = 4.1×103, volume fraction
ranges from 0.13 to 0.5. The results show that the drag force distribution
within the array of cylinders is influenced significantly by volumefraction. The drag coefficient increases with volume fraction, andunexpectedly the drag coefficients of some cylinders within the array arelarger than that of a single cylinder, which should receive attention inreal practice. At low volume fraction, the flow field is dominated bysmall scale vortices, however with the increase of volume fraction, thesmall scale vortices are attenuated and large scale vortices are dominant.

The forces and flow field of flow around multiple cylinders are more
complex than a single cylinder, and the total drag coefficient of multiple
cylinders could not be estimated accurately by the drag coefficient of asingle cylinder. Flow around multiple cylinders has received muchattention. Both experimental and numerical results show that the totaldrag coefficient of a circular array of cylinders increases with volume
fraction (NICOLLE and EAMES (2011), Yu et al. (2013), Chang andConstantinescu (2015)). And different from a circular array of cylinders,flow around a square array of cylinders will be also affected by incident
angle. The most earliest work about flow around four cylinders arrangedin square was conducted by Sayers (1988, 1990). The total dragcoefficient is the most concerned parameter in previous studies (Pearceyet al. (1982), Lam and Lo (1992), Lam and Fang (1995), Lam et al.
(2003a), Lam et al. (2003b), Lam et al. (2008), Lam and Zou (2010),
Sonnenwald et al. (2019)), and less attention has been pay to therelationship of flow field and the force on each cylinder within the array.
The total force of array as well as force on each cylinder is the same
important in the construction process. Therefore, in the present work
flow around a square array of cylinders is investigated numerically, andfoci are paid to the flow filed and force distribution within the cylinders.

KEY WORDS: Volume fraction; square cylinders; dragcoefficient; flow field
INTRODUCTION
The pile-group foundation is widely used is real practice. It is ofimportance to accurately estimate the current force on the piles as wellas understand the flow filed around and within the piles. Flow around thepiles is complicated due to the interaction among piles, and the force
characteristics and flow field have not been investigated completely yet.
Therefore, it is necessary and valuable to investigate the current force
and flow field for the pile-group foundation.

NUMERICAL SIMULATION METHOD
The 4.0 version of OpenFOAM was used for all numerical simulations,for more details please refer to Weller et al. (1998). The Reynoldsaveraged equations for conservation of mass and momentum are givenbyThe classical problem of flow around a circular cylinder has beenbroadly investigated due to its practical importance in engineering
applications. For example, experiments have been carried out by Trittonand D. (1959), Roshko (1961), Sabersky and Acosta (1964), Schewe(1983), Sumer and Fredsøe (1997), Graf and Yulistiyanto (1998) and2105