CFD Analysis of Pressure Variations on Airtight Platforms for Offshore Wind Turbines Monopile Foundation

Abstract Airtight platforms within wind turbine generator (WTG) monopile foundations are widely implemented to improve moisture control, durability, and operational performance. In offshore monopile foundations, an air-tight platform helps prevent water from entering the space inside the foundation structure. This is important because it keeps the internal environment dry and protected from corrosion or damage caused by water exposure However, it is currently unknown whether such a design can lead to pressure variations caused by fluctuating water levels inside the monopile, arising from water exchange between the sea and the monopile through cable entry and stress relief openings. This study assesses pressure variations inside monopiles using computational fluid dynamics (CFD). The CFD models simulate extreme wave conditions, incorporating appropriate boundary conditions and non-linear wave theories based on water depth and wave steepness. A time-domain relationship between wave heights on the internal and external water surfaces and resulting pressure variations over time is established. The analysis highlights key parameters, such as the initial air column height and vent hole elevation, which critically influence the pressure variations and structural integrity of the airtight platform. A structured workflow is presented for accurate pressure calculations, enabling robust and optimized monopile foundation designs. This research provides engineers and researchers with actionable insights to mitigate high pressures and variable loading on airtight platforms, contributing to the advancement of WTG monopile foundation designs under nonlinear wave conditions.