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This study investigates the unsteady aerodynamic characteristics of urban trains passing through most criticallength tunnels through numerical simulations. The threedimensional unsteady Reynoldsaveraged NavierStokes (RANS) equations coupled with the Renormalization Group (RNG) kɛ turbulence model were employed to analyze the aerodynamic behavior of an urban train operating at 160 km/h. The results reveal that train operation significantly modifies the flow field structure and pressure distribution within the tunnel, characterized by distinct regional patterns. These modifications are primarily attributed to two factors: the propagation and reflection of traininduced pressure waves, and the compression effect of the train body on the tunnel air. Significant differences are observed between pressure variations on the train surface and tunnel wall monitoring points. While the train surface pressure is predominantly influenced by the arrival timing of compression and expansion waves, the tunnel wall pressure exhibits more complex evolution patterns due to the combined effects of train disturbances, pressure waves, and lowpressure regions. The aerodynamic drag is mainly pressureinduced and significantly affected by both blockage effects and pressure waves. Furthermore, distinct unsteady aerodynamic responses are observed among different car bodies: the first three cars are primarily affected by entrance and exit disturbances, while the rear five cars experience additional pressure wave effects, resulting in substantial fluctuations in lateral force, rolling moment, and yawing moment.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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