Impact of wind barrier structures on the flow field around railway bridges under crosswind: A study based on real terrain in Xinjiang, China

This paper presents the influence of an innovative wind barrier designed to mitigate the effects of crosswinds on high-speed train operating areas in mountainous regions based on typical terrain in Xinjiang, China. The study employs the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations combined with an unstructured hexahedral volume mesher to simulate airflow around cross-scale structures, and the simulation method has been validated through wind tunnel tests. First, the test results confirm the numerical method's advantage in cross-scale geometric model computations. Second, this paper examines airflow characteristics upstream of the bridge in the basic model of typical terrain (BMTT). Results show multiple high-velocity zones within the terrain. Notably, the bridge high-speed zones pose a risk to train safety, caused by valley-influenced airflow compression toward the central bridge along the rail direction, combined with downhill winds driven by terrain and gravity effects. Third, comparing the anti-crosswind performance of the original porous case (OPC) and the diffusible diversion case (DDC) reveals that the DDC is more effective in reducing crosswind effects on train operating areas. By deflecting airflow upward and downward, DDC creates reverse flow zones at tracks 1 and 2 regions. It blocks crosswinds over 86.7 % of its area and diverts 74.1 % of crosswinds away from train operating areas, enhancing wind barrier performance by 44.2 %.