## 4 Characteristics of Outdoor Wind Field at National Sliding Centre  
Through CFD simulation, the wind field distribution information, including the wind speed distribution and wind pressure distribution, of the NSC under different climate conditions in Yanqing District in winter is obtained. The output simulation results are in the Supplementary Materials. Based on the CFD simulation results of Yanqing's average winter wind level of 3.125 and different wind directions, we analyzed the outdoor wind field characteristics of the NSC. For the CFD simulation results of the NSC when the wind direction is WNW, we found the following:  
(1) Area I  
The air in the windward region of the venue in Area I separates and refluxes due to collision with the track. Air separation zones are formed on the north and south sides of the venue in Area I, and air retention zones are formed in the windward region, with wind speeds ranging from approximately 1.81 m/s to 3.53 m/s. The venue region interacts with the incoming wind, and the wind speed changes relatively greatly, ranging from approximately 0.0003 to 6.96 m/s. Due to the shielding effect of the venue in Area I on the incoming wind, there is an obvious low wind speed zone in the leeward region of the venue, and even a large zone of no wind. The minimum wind speed in the leeward region is as low as 0.02 m/s. The wind pressure difference in the windward region of Area I is large, with the wind pressure ranging from about 0.91 Pa to 5.93 Pa, and the average wind pressure is 1.99 Pa. Due to the interaction between the venue in Area I and the incoming wind, a large-scale negative pressure zone is formed in the leeward region, with the wind pressure ranging from about \(-\)3.57 Pa to \(-\)0.22 Pa, and the average wind pressure is \(-\)1.37 Pa. The pressure difference between the windward region and leeward region is about 9.50 Pa. The wind speed in the venue region of Area I changes rapidly, forming vortices and complex wind fields, with a maximum wind speed value of 6.96 m/s; the global wind speed dispersion \(\overline{L}_{1}^{1}\) of the venue region of Area I reaches 2.0194; and the wind field distribution is extremely uneven. (2) Area II  
The air in the windward region of Area II forms air backflow due to collision with the track, and an air stagnation zone is formed in the windward region, with wind speed ranging from about 1.99 m/s to 3.80 m/s. The venue region of Area II interacts with the incoming wind, and the wind speed varies greatly, ranging from about 0.0022 to 7.76 m/s. Due to the shielding effect of the venue on the incoming wind, there is an obvious low-wind  
Figure 8: Wind field when wind direction is NWN. speed zone in the leeward region, and even a small zone of no wind, with the minimum wind speed in the leeward region as low as 0.20 m/s. The wind pressure in the windward region of Area II varies greatly, ranging from \(-\)0.62 Pa to 5.71 Pa, with an average wind pressure of 0.40 Pa. Due to the interaction between the venue and the incoming wind, a large negative-pressure zone is formed in the leeward region, with wind pressure ranging from \(-\)3.24 Pa to 0.45 Pa, and an average wind pressure of \(-\)0.12 Pa. The pressure difference between windward region and leeward region is about 8.95 Pa. In the venue region of Area II, the wind speed distribution is uneven, the wind speed changes rapidly, forming vortices and complex wind fields, and there is a maximum wind speed value of 7.76 m/s. The global wind speed dispersion \(\overline{\text{L}}_{2}^{1}\) in the venue region of Area II reaches 0.1984. (3) Area III  
The air in the windward region of the venue in Area III is separated due to collision with the track. The separated air flows along the 360\({}^{\circ}\) curved loop until it reaches the north and south sides of the track. After that, the air leaves the track and flows around. Another part of the air in the windward region collides with the track and forms an air retention zone, with a wind speed ranging from about 1.93 m/s to 3.64 m/s.