To study the influence of L-shaped flow deflectors on the vortex-induced vibration (VIV) characteristics of steel box girders, a series of 20 test cases was designed. A sectional model wind tunnel test was carried out under a +5° wind attack angle to analyze the VIV response patterns associated with variations in horizontal plate width and vertical plate height. In parallel, computational fluid dynamics (CFD) simulations were performed, and the vortex structures were extracted using the Ω vortex identification method to reveal the underlying VIV evolution mechanism. The results show that increasing the horizontal plate width significantly enhances the suppression of vertical bending VIV, while shifting the VIV lock-in region toward higher wind speeds. In contrast, the vertical plate height strongly influences torsional VIV; larger heights tend to induce torsional vibration in the high wind speed regime. Flow field analysis shows that widening the horizontal plate reduces the spanwise extent of vortex structures, thereby improving flow uniformity. Conversely, increasing the vertical plate height promotes the formation and development of vortex clusters, leading to a more complex flow field. Effective vibration mitigation is achieved only when the vortices generated by the attached components are of a comparable scale to those shed from the main girder, enabling interference with the dominant vortex-shedding process.

To investigate the distribution characteristics of wind parameters near shorelines, a two-dimensional geometric model is developed using computational fluid dynamics (CFD). The study employed the SST k-ω turbulence model and a multiphase flow model to simulate wind parameter distributions under the influence of two-dimensional wind over calm water. The effects of fetch distance, water depth, incoming wind speed, and underwater terrain slope on the distribution characteristics were analyzed. Results indicate that for fetch distances belowe 60 m, wind speed near the water surface exceeds the inlet wind speed, demonstrating an acceleration effect. Beyond 60 m, wind speed increases with height until stabilizing at a specific elevation. Terrain slope variations exhibit negligible effects on wind parameter distribution, while water depth shows strong correlations. Deeper water leads to a nonlinear increase in gradient wind height and significantly alters wind speed profiles. Although inlet wind speed does not affect gradient wind height or wind structure, it does impact the near-surface acceleration effect.