Dynamic collapse initiation and propagation in submarine pipelines: A fluid–structure interaction study

Abstract

The dynamic propagation of collapse in submarine pipelines is strongly influenced by fluid–structure interaction (FSI), yet its quantitative effects remain insufficiently characterized. This study investigates the role of the surrounding fluid on collapse propagation dynamics through numerical simulations and experimental validation. Quasi-static analyses using the Riks method are employed to estimate collapse and propagation pressures, while fully dynamic simulations using a Coupled Eulerian–Lagrangian (CEL) formulation capture transient FSI effects. Results show that FSI significantly alters propagation behavior, reducing collapse velocity by approximately 40% compared to vacuum conditions. Energy analyses reveal a marked redistribution of contributions: structural dissipation accounts for more than 90% of the external work in vacuum but decreases to approximately 70%–75% under FSI, indicating substantial energy transfer to the surrounding fluid. This behavior is associated with fluid inertia, added-mass effects, and enhanced dissipation. Transient pressure pulses generated by rapid fluid acceleration and impact are captured, exhibiting clear spatial–temporal evolution governed by inertia-driven fluid response and wave propagation. Validation against experimental data shows excellent agreement, with a mean absolute percentage error (MAPE) of approximately 1.17% and R 2 = 0.9967 . These findings highlight the importance of realistic fluid modeling and provide insights relevant to the design of deepwater pipelines and buckle arrestors.