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

The dynamic response of a self-induced elastic beam attached to a cylinder in channel flow
Fangyu Gong, Peng Li*, Hongde Qin, Zhongchao Deng

College of Shipbuilding Engineering, Harbin Engineering UniversityHarbin, Heilongjiang, China

deformation of filament and the change of flow field. Many scholars
have done a lot of research from the perspectives of physicalexperiments, numerical simulations, and theoretical analyses.
Zhang et al. (2000) found that the filament has two different stablemotion states through experimental research on the filament in theflowing soap film. The stretched straight state (SS) is similar to thefish gliding state. In this state, the vortex falling off the filament ismainly concentrated at the tail of the filament, and the von Karmanvortex street is generated in the wake, there is little tendency ofboundary layer separation in the middle of filaments; Secondly, theisolated beating state is similar to the swimming state of fish. Zhu et al.
(2009) used the immersion boundary method to numerically simulate
the two filaments in series, studied and analyzed the resistancechanges of the two filaments at different distances and different
Reynolds numbers, and found that the resistance of the filaments at theback will be reduced compared with the isolated filaments. Jeong et al.
(2021) studied the interaction of two series filaments near the single
wall and double parallel wall, found that the near-wall will greatly
improve the drag reduction effect between the two filaments, andexplored the relationship between this effect and the characteristics ofwake vortex generated by them. Park et al. (2018) used the immersion
boundary method to numerically simulate the flexible filaments inseries, diagonal, triangular, and diamond configurations, and exploredthe effect of the position arrangement in multiple filament groups on
the propulsion efficiency. Weihs et al. (1983) found that the rhombic
fish school with two continuous fish staggered is a typical optimal
configuration, which can save the total energy consumption. Zhu et al.
(2014) studied two flapping flexible filaments arranged in series using
the immersion boundary method and found that the vortex structure
plays an important role in reducing the motion consumption of thefollower. Li et al. (2020) directly measured the energy consumption offish schools during swimming using bionic robotic fish and found aswimming strategy matching the phase of surrounding vortices. It canbe seen that the force on the flexible strip in the vortex field has animportant impact on it, and the research on the interaction between theflexible strip and the surrounding flow field is of far-reachingsignificance. Through the study of the dynamic response of flexible
strips in the flow field, we can explore various natural phenomena offlexible individuals in the group, such as fish flocking and walking,and solve the configuration problem of each flexible structure in theABSTRACT
In this paper, the dynamic response of a self-induced elastic
deformation of a beam attached to a cylinder in channel flow werestudied in the two-dimensional flow regime. We explored the responseof the elastic deformation of a beam for a wide range of geometricfeatures. The vortex falling off behind the cylinder leads to theflapping of the elastic beam, and the existence of the elastic beamaffects the vortex shedding behind the cylinder. By changing thelength of the elastic beam behind the cylinder, the flap motion of thefree end of the elastic beam was observed, while the flow exhibit avariety of vortex-shedding patterns.

KEY WORDS: Arbitrary Lagrangian-Eulerian (ALE); Fluidstructure interaction (FSI); Vortex shedding.

INTRODUCTION
Studying the motion mechanism and internal essence of flexible
structure in fluid is of great significance to explain many biologicalphenomena, and puts forward new ideas for biological hydrodynamics.
The study of flexible structures in low Reynolds number flow is
helpful for understanding. For example, starting from the biologicalbehavior that cats use their whiskers to perceive the flow field changes
caused by mouse movement, the study of the symmetry-breaking
behavior of flexible filaments in Stokes flow provides inspiration forthe development of highly sensitive flow sensors (Deng, 2021); And
microorganisms push the body through flagella (Deng, 2007).
Relevant studies show that the group behavior of fish is of greatsignificance in defending predators (Tchieu, 2016) and (Shaw, 1978),increasing predation and reproduction opportunities (Pitcher, 1982)
and (Weihs, 1983), saving energy consumption, (Mark, 1987) and(Zhu, 2009). It is found that fish will detect and use the vortices
around them to greatly improve their swimming efficiency. Therefore,
the interaction between the flexible filaments and surrounding water isan important problem that cannot be ignored in the research of flexible
filaments. It can also provide a scientific basis for the design of a newgeneration of underwater vehicles and the arrangement andcombination in the process of performing tasks. The interaction
between flexible filament and flow field involves the large

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