Abstract
This study investigates the wind flow field around the Seto-Ohashi Bridges during typhoon KROSA in 2019, using the Weather Research and Forecasting Model (WRF). Three WRF Large Eddy Simulation (WRF-LES) models, i.e., 1.5 order Turbulence Kinematic Energy (1.5TKE) closure model, Smagorinsky (SMAG) model, Nonlinear Backscatter and Anisotropy (NBA) model, and YSU Planetary Boundary Layer (PBL) scheme were tested to evaluate their performance for reproducing the wind flow filed around the Seto-Ohashi Bridges. The correlation coefficient between the simulated and observed 10-minute mean wind speed and direction showed no significant difference between the LES models and the YSU PBL scheme. Additionally, no significant variation in gust factor reproduction was observed. During typhoon KROSA passage, the maximum wind speed was observed at Hitsuishijima Viaduct with an approaching east wind, when typhoon centre started to land on Shikoku Island. Owing to the terrain blockage effect of Shikoku Island, significant variation of wind speed and direction along the Seto-Ohashi Bridges was observed, when the wind came from east and southeast. This result highlights the influence of local terrain on the wind flow field of the Seto-Ohashi Bridges.
