Simulation Methodology to Study the Effect of Fluid-Structure Interaction on Dynamic Behavior of Flexible Pipes

A numerical simulation methodology that enables assessment for the impact of fluid flow on the slender piping system’s dynamics has been discussed in this paper. The fluid-structure interaction involves many different complex phenomena like water hammer, cavitation which can also affect the dynamics of the overall system but this paper highlights on the influence of fluid flow velocities and piping designs on dynamic responses of the system. A co-simulation between structure and fluid dynamics is performed in Abaqus to evaluate the dynamic behavior of the piping system. The flexible pipes are excited with dynamic loads capturing the modal behavior of the system and displacements are considered as a measure for relative comparison. The free vibration response, after the removal of load, is also used to evaluate the damping characteristics of the overall system subjected to different fluid flow conditions. The main objective of this method is to provide an opportunity for the analysts to come up with alternate ways to capture the variation in responses in time domain simulations and to account for such changes in frequency domain simulations as well. The modified dynamic responses can simply be captured in frequency domain by tuning some parameters like structural or modal damping. In this paper, time domain analysis are performed to study the impact of different flow velocities on dynamic behavior of the overall system. Tuning the parameters in frequency domain becomes a complete different study and is not considered in the scope of this paper. Capturing the fluid flow effects in steady state dynamics analyses and consequently overcoming the conventional approach of assuming some damping value are the major focus of this study. Along with flow velocity studies for two different pipe designs, the effect of artificial stiffness induced due to fluid flow in curved design is also discussed. The results are also compared with the conventional modelling approach where the fluid is modelled as a non-structural mass.