**5. The results and discussion**

In the present section, the effects of barriers with the inclined angle (nine types) on the flow field and aerodynamic forces and moments are discussed in form of velocity contours, velocity vectors, total pressure contours, turbulence intensity contours, and aerodynamic force.

**Figure 3** shows the effects of barriers with the inclined angle on the velocity contours around the train. When there is no barrier, the high flow velocity can be found at the upper windward of the train as the flow approaches the train. A large low-velocity zone occurs on the leeward side, which is the left side due to the inflow direction. Meanwhile, the high-velocity gradient is generated on the top of the train. It is obvious that the flow velocity around the train is rather uneven, leading to a considerable negative influence on the stability of the train. As the barriers are introduced, the flow velocity around the train becomes more even, and the flow pattern changes substantially. When *θ* = 0°, the right barrier takes the place of the train to withstand the crosswind. As a result, the line of a large velocity gradient is formed

#### **Figure 3.**

*The velocity contours (a) without barriers, (b) θ = 0°, (c) θ = +2.5°, (d) θ = +5.0°, (e) θ = +7.5°, (f) θ = +10.0°, (g) θ = 2.5°, (h) θ = 5.0°, (i) θ = 7.5°, and (j) θ = 10.0°.*
