An analytical approach to wake interference effects on circular cylindrical structures

When a body is immersed in the wake of another body the additional buffeting force due to the vortices shed from the upstream structure magnifies the amplitude of vibration of the downstream structure. The proposed semi-empirical model is of the coupled Rayleigh wake-oscillator type with the equation of motion including an additional buffeting force. For two structures consisting of different structural parameters and placed in tandem with a wind flow, the buffeting force experienced by the downstream structure can be extrapolated from the lift force of the upstream structure, by using the ratios of the Scruton number, for the two structures. The paper highlights the aerodynamic response of tandem structures in the three primary interference regions: the proximity interference region, where the separation of the structures lies between 1.0D and 1.1D; the proximity induced galloping region where the separation lies between 1.1D and 3.8D; and the wake interference region where the separation is greater than 3.8D.