Frequency and Time-domain Analyses of Pipelines Anchored Against Longitudinal Movement

Frequency and time-domain approaches are used for the assessment of fluid-structure interaction during steady-oscillatory flows in straight pipe systems conditioned to anchor blocks. The first is developed based on the transfer matrix method (TMM), allowing the assessment of the system in terms of frequency response, while the second is based on the method of characteristics (MoC), allowing the assessment of wave propagation. Axial vibration of the fluid and the pipe-wall are solved and coupled by means of Poisson and junction coupling. The models are finally used to reproduce the performance of a marine outfall which steady-oscillatory flow is induced by the exposition to sea waves at the downstream pipe boundary. The complementarity of both approaches allows the co-verification of the models. Frequency-domain output enables the assessment of resonance frequencies for different pipe setups, while time-domain output allows a deeper insight of wave propagation.