Numerical methodology for evaluating the effect of sleepers in the underbody flow of a high-speed train

Abstract

This paper presents an innovative numerical methodology based on dynamic meshes that allow for the 3D simulation of the motion of a high-speed train, reproducing the real movement and including the geometry of the sleepers in the calculation. The objective of this strategy is to provide a more accurate analysis of the underbody flow, which has become a matter of concern, especially because of the rising problem of the ballast flight. The proposed methodology, without sleepers, has been compared to the conventional procedure, consisting of a static train and a moving wall condition on the ground, with satisfactory results. Subsequently, the inclusion of the sleepers in the simulation revealed an increase in the drag coefficient of approximately 15%. Regarding the underbody flow, lower values of the minimum static pressure were observed in the entire profile from the ballast layer to the train and some strong peaks of the vertical component of the velocity were identified near the sleepers. Both factors could affect the process of ballast flight, which is estimated to be favoured by the presence of the sleepers. The results obtained demonstrated the applicability of the proposed methodology.