The 12th International Conference on Scour and Erosion (ICSE 2025)

Physical model tests and computational fluid dynamics (CFD) simulations were conducted to gain deeper insight into scour development around a submerged energy storage system. This system comprises flexible bladders, an oval-shaped vertical shaft, and ducting installed on the seabed, all interacting with the local hydrodynamics. Various hydrodynamic conditions, geometries, and orientations were tested to assess a range of expected scour patterns in an offshore environment. The results showed that scour developed rapidly around the vertical shaft, reaching depths of up to 6.0 m, depending on its orientation relative to the dominant current direction. In contrast, scour in the wake of the flexible bladders evolved over longer timescales and was more influenced by their orientation. The CFD model was used to investigate the importance of scale effects by comparing predictions at both lab and field scale. The results show good consistency between lab and field scale predictions, where the scour around the shaft develops quicker than the scour behind the bladder. This further demonstrates the applicability of CFD for understanding field scale scour behavior, both in time development and spatial extent.