Flow-induced vibration of a flexible triangular cable at low Reynolds numbers

Abstract

Flow-induced vibrations of an infinite long flexible cable with a triangular cross section allowed to oscillate in the cross-flow direction are numerically studied based on a high-order spectral element method at Re = 100 and 200. A tensioned beam model governs the dynamics of the triangular cable and the selected tension leads to single wave vibrations. The main focus of the present study is to explore the response of the flexible triangular cable, with the aim of providing new insights into the essential features of flow-induced vibrations of the long flexible body with an asymmetric cross section. The numerical results show that for the angle of attack α = 60° in which one of the sides of the triangular cable is facing the incoming flow, the oscillation of the cable is dominated by vortex-induced vibrations (VIVs) at Re = 100, while a combination of strong VIV and weak galloping is excited at Re = 200. As compared to the flow past a flexible cable with a circular cross section at the same conditions, the dynamics responses of the triangular cable are significantly vigorous, which is evidenced further in energy transfers and wake dynamics as well. It is also revealed that the secondary vortex generated at the trailing edge of the triangle plays an important role in the wake evolution process. Finally, additional simulations at α = 0° are conducted and the results show that the responses are suppressed strikingly with very weak amplitudes, implying that the wake dynamics is desynchronized against the vibration of the flexible cable.