Wake interference in monopile–cable systems under transcritical conditions

As offshore wind power expands into deeper waters, the hydrodynamic interference between large-scale wind turbine foundations and transmission cables has become increasingly prominent. This study employs the shear-stress transport k–ω turbulence model to numerically simulate the three-dimensional flow field and structural loading characteristics of a monopile foundation and its adjacent cables. Unlike previous studies focused on subcritical flow, this research investigates transcritical flow conditions (Re ≈ 6 × 106) representative of realistic offshore environments. The study systematically analyzes how different cable spatial layouts (θ = 0°, 45°, 90°, 135°, and 180°, where θ denotes the angle between the incoming flow direction and the cable orientation) affect the wake vortex structure, vortex shedding characteristics, and hydrodynamic forces. Results indicate that the cable orientation significantly alters wake symmetry and stability. Specifically, the 135° arrangement triggers a “shear layer locking” effect, leading to the strongest flow field asymmetry with a root-mean-square lift coefficient (CLRMS) of 0.195 and a mean drag coefficient (CDM) of 0.519. Furthermore, the cable experiences dramatic force fluctuations at 45° due to gap flow acceleration (Venturi effect), with the root-mean-square lift coefficient (CLRMS) reaching 0.458. These findings provide critical reference data for the fatigue design of cable protection systems in high-energy tidal environments.