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Wind and Structures Volume 35, Number 5, November 2022 , pages 309-322 DOI: https://doi.org/10.12989/was.2022.35.5.309 |
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Study on the transient flow induced by the windbreak transition regions in a railway subject to crosswinds |
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Zheng-Wei Chen, Syeda Anam Hashmi, Tang-Hong Liu, Wen-Hui Li, Zhuang Sun, Dong-Run Liu, Hassan Hemida and Hong-Kang Liu
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| Abstract | ||
| Due to the complex terrain around high-speed railways, the windbreaks were established along different landforms, resulting in irregular windbreak transition regions between different subgrade infrastructures (flat ground, cutting, embankment, etc). In this paper, the effect of a windbreak transition on the wind flow around railways subjected to crosswinds was studied. Wind tunnel testing was conducted to study the wind speed change around a windbreak transition on flat ground with a uniform wind speed inflow, and the collected data were used to validate a numerical simulation based on a detached eddy simulation method. The validated numerical method was then used to investigate the effect of the windbreak transition from the flat ground to cutting (the "cutting" is a railway subgrade type formed by digging down from the original ground) for three different wind incidence angles of 90°, 75°, and 105°. The deterioration mechanism of the flow fields and the reasons behind the occurrence of the peak wind velocities were explained in detail. The results showed that for the windbreak transition on flat ground, the impact was small. For the transition from the flat ground to the cutting, the influence was relatively large. The significant increase in the wind speeds was due to the right-angle structure of the windbreak transition, which resulted in sudden changes of the wind velocity as well as the direction. In addition, the height mismatch in the transition region worsened the protective effect of a typical windbreak. | ||
| Key Words | ||
| computational fluid dynamics (CFD); crosswinds; flow structures; railway; windbreak transition; wind tunnel test | ||
| Address | ||
| Zheng-Wei Chen:Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China Syeda Anam Hashmi and Hassan Hemida: Birmingham Centre for Railway Research and Education, School of Civil Engineering, University of Birmingham B15 2TT, UK Tang-Hong Liu, Wen-Hui Li, Dong-Run Liu and Hong-Kang Li: Key Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha 410075, PR China Zhuang Sun:Chengdu Fluid Dynamics Innovation Center, Chengdu 610072, PR China | ||