A computational study on aerodynamic characteristics of a simplified high-speed train: The effects of crosswinds and surface roughness

The airflow around a simplified train model is investigated using a three-dimensional gamma - (Re) over tilde (theta t) transitional approach. Four different yaw angles (theta = 10 degrees, 20 degrees, 30 degrees, and 40 degrees) 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.