Numerical comparison of aerodynamic performance of stationary and moving trains with or without windbreak wall under crosswind

The aerodynamic performance of stationary and moving CRH2c trains with or without a windbreak wall under crosswind was simulated by DDES based on the SST κ-ω turbulence model. In this paper we present a comparison between the pressure on and around the trains, velocity around the trains, and the forces experienced by trains. Our work is an attempt to understand the difference in the aerodynamic performance between stationary and moving trains with or without a windbreak wall under crosswind. In addition, our study aims to determine whether the method applicable to stationary trains could replace that for moving trains. The numerical algorithm used in this simulation is verified by comparing its results with those obtained in a wind tunnel test. The results show that for a train without a windbreak wall under crosswind, the method for stationary trains can replace that for moving trains to simulate the pressure field around and the aerodynamic forces of a train, although the results may be relatively conservative. Furthermore, the aerodynamic forces of the tail car are almost insensitive to the train motion; however, for the simulation of the velocity field around the train, replacement of the method for moving trains by that for stationary trains requires careful consideration. The results showed that, for a train with a windbreak wall under crosswind, the method for moving trains cannot be replaced by that for stationary trains because the new vortices that are produced close to the body of the train by the windbreak wall are significantly affected by the motion of the train.