Numerical investigation of flow patterns and sheltering effects around jacket foundations under varying attack angles

Jacket foundations, prevalent in offshore wind installations, face local scour threats during service life. While existing studies have experimentally and numerically investigated local scour and flow fields around such foundations, research correlating flow characteristics with local scour under varying attack angles remains scarce. This study employed test conditions and scour bathymetries from previous flume tests, aims to employ numerical modeling to examine flow-structure interactions around jacket foundations subjected to four flow attack angles (0°, 15°, 30°, 45°). Results demonstrate equilibrium scour volumes around jacket foundations increase by 70.8% (15°), 76.8% (30°), and 28.0% (45°) relative to 0° due to varying sheltering effects at different attack angles. The flow intensities at the front piles of the jacket foundation remain consistent across different attack angles, whereas the sheltering effect reduces flow intensity at the rear piles. Equilibrium scour depths at rear piles decrease under 0° and 45° angles owing to sheltering effects, but increase under 15° and 30° angles due to contracted flow, demonstrating a strong correlation between equilibrium scour depth and flow intensity at rear piles. A dimensionless sheltering coefficient ( C s h ) is proposed to correlate with total scour volumes ( V s / D 3 ) at the jacket foundation, establishing a strong linear relationship. For engineering practice, alignment with dominant flow direction proves advantageous for scour protection and cost reduction for jacket foundations. • Flow patterns and sheltering effects around jacket foundations are numerically investigated for four attack angles. • Attack angle significantly alters flow contraction and sheltering, impacting scour volume and distribution. • Minimum total scour volume occurs at 0° attack angle; 15° and 30° angles induce up to 70% increase. • A dimensionless sheltering coefficient ( C s h ) is proposed to correlate with total scour volumes ( V s / D 3 ) .