A DES study of the flow around a full-scale train under crosswind condition

Abstract

A numerical study on the flow around a full-scale train subjected to crosswind has been conducted on the basis of detached-eddy simulation (DES). Finite-volume method is applied to unstructured mesh generated around a three-car-train model whose running speed is fixed to 120 km/h while the crosswind speed is set to 5 m/s,15 m/s, and 25 m/s. A clear longitudinal vortex structure is recognized in the case of the crosswind speed of 25 m/s, where two longitudinal vortices are evolved respectively from the roof and floor of the head car (roof-edge and floor-edge vortices), forming a characteristic vortex pair. This longitudinal vortex structure around the head car is discussed with a focus on its non-trivial role in the side-force mechanism. Our simulation suggests a causal association between these two vortices, which implies an importance of optimum designing of the underfloor equipment in addition to the roof and head shapes of the head car.