A State-of-the-Art Review of the Hydrodynamics of Offshore Pipelines Under Submarine Gravity Flows and Their Interactions

Submarine gravity flows, e.g., debris flows and turbidity currents, pose a significant threat to offshore pipeline integrity. This risk primarily manifests through the imposition of substantial dynamic loads on pipelines or their large displacement when impacted by such flows. To enhance our understanding of these threats and facilitate the development of more robust pipeline design and protection strategies, this work reviewed the interactions between submarine gravity flows and offshore pipelines. For an individual pipeline, critical focus lies in characterizing the influence of key parameters—including Reynolds number, span height, impact angle, pipe geometry, ambient temperature, and surface roughness—on both the resultant impact forces and the fluid-structure interaction dynamics. Then, investigations into the interactions between gravity flows and multiple pipes are summarized, where the in-line spacing distance between two pipes is a key factor in reducing the impact force. Further, flow-induced vibration responses of a single pipeline and two tandem pipelines under gravity flows are presented. Building upon a thorough review, we conducted overall evaluations. There are few experimental studies and most investigations ideally treat the seabed to be horizontal, which does not always occur in practical engineering. Choosing empirical formulas to evaluate hydrodynamic loads should carefully consider the specific working conditions. An appropriate non-Newtonian fluid model is significantly important to avoid uncertainties. Some practical risk reduction measures such as streamlined structures and reduction in roughness are recommended. Finally, suggestions for future study and practice are proposed, including the requirement for three-dimensional numerical investigations, assessment of fatigue damage by flow-induced vibrations, consideration of flexible pipeline, and more attention to multiple pipelines.