Semnan UniversityInternational Journal of Nonlinear Analysis and Applications2008-682212Special Issue20211201A Computational Study on Aerodynamic Characteristics of a Simplified High-Speed Train: The Effects of Crosswinds and Surface Roughness519540535210.22075/ijnaa.2021.23992.2647ENAlireza HajipourDepartment of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran0000-0002-0301-5449Arash Mirabdolah LavasaniDepartment of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, IranMohammad Eftekhari YazdiDepartment of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, IranJournal Article20200616The airflow around a simplified train model is investigated using a three-dimensional $\gamma-\widetilde{Re}_{\theta t}$ transitional approach. Four different yaw angles ($\theta = 10^{\circ}, 20^{\circ}, 30^{\circ}$, and $40^{\circ}$) perpendicular to the body of the simplified train model are considered which the magnitude of front air-flow is constant, and the magnitude of crosswind determines by yaw angle. The main aim of the research is to investigate the influences of the yaw angle and roughness on the time-averaged flow structure, turbulent quantities such as turbulent kinetic energy, dissipation rate, and the aerodynamic forces such as skin friction and pressure coefficients. The findings show that the yaw angle has a pronounced influence on the three-dimensional flow structure around the high-speed train. As the yaw angle augments, the aerodynamic forces like skin friction and pressure coefficients increase. Furthermore, the roughness has a negligible effect on the pressure coefficient. Also, the skin friction coefficient locally increases in the rough train body.https://ijnaa.semnan.ac.ir/article_5352_ee4e27f0314bbfd3cf69f3e9ad83ed3b.pdf