Wind barriers on bridges: Effects of wind incidence angle on flow field characteristics

Aerodynamic characteristics of wind barriers on two Croatian viaducts were experimentally studied in the CRIACIV boundary layer wind tunnel. Effects of wind incidence angle on flow field characteristics behind the wind barrier were reported. Mean velocity fields and vorticity fields were determined using the Particle Image Velocimetry (PIV). Freestream velocities were measured using the hot-wire velocimetry and the Pitot tube. Results indicate a possibility of wind-induced instability of high-sided vehicles at larger vertical incidence angles, especially in the traffic lane close to trailing edge of the bridge, as velocity fluctuations and mean freestream velocities approach the road surface when increasing the vertical incidence angle. Removing elements from the wind barrier can result in very large local velocities immediately downstream from the barrier. Variations in horizontal incidence angle do not seem to affect flow field characteristics significantly.