Mutual Influence of Subsea Power Cables and Rock Bags on Their Hydrodynamic Behaviors

Abstract Subsea Rock Bags (RBs), also known as Filter Units (FUs), are cylindrical mesh bags filled with rock aggregates to a certain weight. They are commonly used for scour protection and secondary stabilization of subsea infrastructures, including subsea power cables in offshore wind farms. This study investigates the hydrodynamics of both rock bags and cables by placing them in proximity to assess their mutual influence. To enable a meaningful comparison, tests are conducted on a rock bag with the same shape, both with and without the presence of cables. The results are then compared under different ocean flow conditions. It is found that cables can significantly affect the force magnitudes and dynamics on a subsea rock bag, through changes in local flow conditions and, consequently, the pressure distribution on the rock bag. Conversely, rock bags also introduce local changes to the sectional forces on the cable, although these changes are confined to a few diameters within the rock bags. These findings provide new insights into the forces acting on rock bags and the flow dynamics responsible for their behavior. These outcomes are expected to improve the stability design of rock bags, ultimately reducing the risk of subsea infrastructure damage due to ocean flows.