An analytical model for vibration of clusters of flexible cylinders in turbulent axial flow

This paper describes an analytical model for the flow-induced vibration of clusters of cylinders in axial flow, in the sub-critical flow regime (i.e., at flow velocities below the threshold for fluid-elastic instabilities). The vibration is excited by the random pressure fluctuations in the turbulent flow acting on the cylinders. Correlation of the excitation field is assumed to exist, with appropriate length scales, not only on the same cylinder, but also on adjacent cylinders in the cluster. In the absence of measured correlation functions for the system at hand, numerical calculations were conducted with available pipe-flow correlation functions, due to Bakewell et al., assumed to be approximately valid. Power- and cross-spectral densities of the vibration are presented, as well as r.m.s. amplitudes, for simple systems of two, three and four cylinders, and the characteristics of the flow-induced vibration are then discussed. It is seen that there is remarkable qualitative agreement with measured characteristics of vibration.