CFD Assessment of Directional Wind Loads and Pedestrian-Level Wind Microclimate for a High-Rise Office Complex on Reclaimed Coastal Terrain in Lagos, Nigeria

Abstract

High-rise structures located on open, low-roughness coastal land are subjected to unobstructed wind flows that generate strong aerodynamic loads and potentially hazardous pedestrian-level wind environments. This study presents a direction-resolved Computational Fluid Dynamics (CFD) investigation of wind loading and pedestrian-level wind comfort for a 104 m tall office tower forming part of a stepped administrative complex on Victoria Island, Lagos, Nigeria. Simulations were executed using steady Reynolds-Averaged Navier-Stokes (RANS) equations with the Generalized k-ω (GEKO) turbulence closure in Ansys Fluent. A dual-domain computational framework (an inner cylindrical domain and an outer rectangular domain) enabled 360° directional evaluation across sixteen 22.5° wind sectors by rotating the outer domain interface. Aerodynamic force coefficients (CFx, CFy, CFR) and moment coefficients (CMx, CMy, CMR) were derived across all directions. The critical loading sectors were identified at 315° and 337.5° for maximum resultant shear force coefficients (CFR = 0.88), and at 180° for maximum overturning moment coefficient (CMR = 0.61), aligning closely with dominant regional onshore wind vectors. Quantitative pedestrian-level flow evaluations based on Lawson (LDDC) comfort criteria reveal high-velocity corner streams and downwash acceleration corridors around the tower base (M = U/Uref > 1.3), indicating potential localized discomfort during peak operational conditions. Recommendations are outlined for facade structural design, mitigation through local canopy interventions, and grid-sensitivity protocols.