Vortex-Induced Vibrations (VIV) is a fluid-structure interaction phenomenon that occurs when an object is placed within a fluid flow. This is a common occurrence in marine environments, where structures such as risers, pipelines, and offshore structures are subjected to ocean currents.

When the vortex shedding frequency matches the natural frequency of the object, a resonance condition occurs, which can lead to substantial vibration amplitudes. The vibrations can occur in the cross-flow and/or in-line direction with respect to the incoming flow. VIV can cause fatigue damage and lead to failure in marine structures and needs to be properly understood and mitigated in the design and operation of offshore systems.

I have been involved in an extensive efford reconstructing motions of risers and extracting hydrodynamic databases to predict VIV in unseen flow conditions. The reconstruction of marine riser motions from accelerometer and strain sensor data entails a blend of data collection, processing, and physical modeling. Initially, accelerometers and strain sensors are deployed to capture acceleration and deformation data respectively, across the riser's structure. Following data collection, noise filtering and calibration are essential to ensure accuracy. The accelerometer data is double integrated to derive displacement, while strain data is converted to displacement using material properties and geometric relations, possibly involving finite element analysis for accurate interpretation. A computational riser model is then constructed and compared with the reconstructed motion from sensor data for validation. The process often involves sensor fusion to merge data from multiple sensors for a holistic understanding of riser behavior, which upon analysis, aids in assessing the impact on the marine structure’s safety, functionality, and longevity. This complex process, coupling data analytics with physical modeling, is critical for mitigating risks associated with vortex-induced vibrations and other marine environmental challenges.

Animations fo the reconstructions I have performed in straight and steel catenary risers are linked bellow: