Identification of upper branch for vortex-induced vibration of a circular cylinder at Re = 300

Dorogi, Dániel and Baranyi, László (2020) Identification of upper branch for vortex-induced vibration of a circular cylinder at Re = 300. JOURNAL OF FLUIDS AND STRUCTURES, 98. ISSN 0889-9746


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In this study flow around a circular cylinder undergoing transverse-only vortex-induced vibrations is investigated using a two-dimensional in-house CFD code. The Navier–Stokes equations, the continuity and pressure Poisson equations written for an incompressible constant property Newtonian fluid coupled with the structural equation are solved using the finite difference method. Systematic computations are carried out for different damping ratio values between ζ=0% and 5%. Reduced velocity is varied in U* = 2.5–7.5, while Reynolds number and mass ratio are fixed at Re = 300 and m*=10, respectively. Up until now, researchers have reported an upper branch only at high Reynolds numbers and low m*ζ values. However, in this study we have observed a three-branch behavior (initial, upper and lower branches) at Re = 300 for ζ ≤ 1%. The upper branch is bounded by two gradual phase changes: at the boundary adjacent to the initial branch, the time-averaged phase difference of vortex force, and at the boundary to the lower branch, the time-averaged phase difference of transverse fluid force relative to the cylinder displacement changes between 0° and 180°. Unbounded variations and phase slips are observed in the time-dependent phase differences, which explains the gradual changes in their time-mean values. In some ranges of the upper branch the second harmonic frequency component plays an important role in the spectra of transverse fluid force, which is closely related to the observed asymmetrical vortex structure. Increasing the structural damping above ζ = 1%, only initial and lower branches are found. The comparison of peak oscillation amplitude against an empirical relationship provided in the literature shows very good agreement for ζ ≥ 1%. A Griffin plot is also used for the comparison of peak response data where the currently obtained results and those in the literature collapse onto almost a single curve.

Item Type: Article
Subjects: T Technology / alkalmazott, műszaki tudományok > TJ Mechanical engineering and machinery / gépészmérnöki tudományok
T Technology / alkalmazott, műszaki tudományok > TP Chemical technology / vegyipar, vegyészeti technológia
Depositing User: MTMT SWORD
Date Deposited: 08 Sep 2020 14:00
Last Modified: 08 Sep 2020 14:00

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