Abstract
Flow-induced vibrations of a flexible cantilever plate, placed in various positions behind two side-by-side cylinders, were computationally investigated to determine optimal location for wake-excited energy harvesters. In the present study, the cylinders of equal diameter D were fixed at center-to-center gap ratio of T / D = 1 . 7 and immersed in sub-critical flow of Reynold number R e D = 10 , 000 . A three-dimensional Navier–Stokes flow solver in an Arbitrary Lagrangian–Eulerian (ALE) description was closely coupled to a non-linear finite element structural solver that was used to model the dynamics of a composite piezoelectric plate. The cantilever plate was fixed at several positions between 0 . 5 < x / D < 1 . 5 and - 0 . 85 < y / D < 0 . 85 measured from the center gap between cylinders, and their flow-induced oscillations were compiled and analyzed. The results indicate that flexible plates located at the centerline between the cylinder pairs experience the lowest mean amplitude of oscillation. Maximum overall amplitude in oscillation is predicted when flexible plates are located in the intermediate off-center region downstream of both cylinders. Present findings indicate potential to further maximize wake-induced energy harvesting plates by exploiting their favorable positioning in the wake region behind two side-by-side cylinders.
Highlights
The flow around single cylinder or group of cylinders is a fundamental fluid dynamics problem that has attracted considerable research due to its wide engineering significance
The Reynolds number Re may influence the transition between single and twin vortex streets [7,8]. In their 3D numerical study, Liu et al [9] showed the influence of cylinder inclination on formation of these vortex streets. (iii) When T/D > 2.2, the gap is sufficiently large that both cylinders behaves more as isolated bluff bodies resulting in predominantly symmetric parallel wake patterns that are coupled with a single Strouhal number Strouhal numbers (St) of approximately 0.21 [6]
As piezoelectric effect is affected by their mechanical strains, which occur irrespective of positive or negative direction in plate deflection, we considered taking their vibration amplitude (A) over time and calculated their root-mean-square (Arms) as an indication of the overall level in mechanical strains experienced by the piezoelectric beam, for all 15 cases
Summary
The flow around single cylinder or group of cylinders is a fundamental fluid dynamics problem that has attracted considerable research due to its wide engineering significance. The flow past a cylinder typically involves boundary layer separation/reattachments, free shear layers, and vortex shedding, which induces cylinder vibrations and noise generation These flow dynamics become more complicated when there are interferences or interactions with neighboring cylinders. In this biased flow regime, a narrower and wider wake region forms behind either cylinders, corresponding to higher (Stn ≈ 0.2–0.4) and lower (Stw ≈ 0.1–0.2) vortex shedding frequencies, respectively [6]. Within this regime, the Reynolds number Re may influence the transition between single and twin vortex streets [7,8]. At much higher gaps (T/D > 4.5), any interference associated with proximity of cylinders are negligible and each cylinder behaves as independent bluff bodies with uncoupled flow patterns [3]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call