This investigation deals with numerical solution of complex aerodynamic interactions induced by a high-speed train (HST) entering and passing through tunnels with a closely adjacent gap and without in between. We present evidences that included pressure transient on the train surface and tunnel wall and comparisons between slipstreams and aerodynamic loads. The results show that two closely adjacent tunnels with a gap does not induce pressure differences on the tunnel wall, in relation to pressures otherwise observed on the single long tunnel, but slightly affects the friction component of the initial pressure rise on the train surface. In addition, the peak values of the slipstreams on the side nearest to the train inside the second tunnel are larger than those recorded when the train passed the first tunnel, suggesting that the existence of a gap between tunnels affect the airflow within the second tunnel. Peak drag coefficients for the train travelling through the first and second tunnel match while being 9.8% lower than the corresponding value observed within a single yet longer tunnel. The study highlights the differences on train aerodynamics when in transit through closely adjacent tunnels and a long tunnel to conclude that improved aerodynamic performances should be considered as the train circulates through closely adjacent tunnels as opposed to through a single passage. The study provides an aerodynamic guideline and reference for the tunnel engineering.

这项研究涉及由高速列车（HST）引起的复杂空气动力学相互作用的数值解，该高速列车进入并通过具有紧密相邻间隙且在两者之间没有间隙的隧道。我们提供的证据包括火车表面和隧道壁上的瞬态压力以及滑流和空气动力载荷之间的比较。结果表明，相对于在单个长隧道上观察到的压力，两个紧密相邻的带有间隙的隧道不会在隧道壁上引起压力差，但是会稍微影响列车表面初始压力上升的摩擦分量。此外，第二隧道内最靠近火车一侧的滑流的峰值大于火车经过第一隧道时所记录的峰值，这表明隧道之间存在缝隙会影响第二个隧道内的气流。通过第一条隧道和第二条隧道的列车的峰值阻力系数相匹配，但比在一条更长的单个隧道中观测到的相应值低9.8％。该研究强调了火车在通过紧密相邻的隧道和较长的隧道运输时空气动力学的差异，得出结论，当火车通过紧密相邻的隧道而不是通过单通道通过时，应考虑改善空气动力学性能。该研究为隧道工程提供了空气动力学的指导和参考。比在单个但更长的隧道中观察到的相应值低8％。该研究强调了火车在通过紧密相邻的隧道和较长的隧道运输时空气动力学的差异，得出结论，当火车通过紧密相邻的隧道而不是通过单通道通过时，应考虑改善空气动力学性能。该研究为隧道工程提供了空气动力学的指导和参考。比在单个但更长的隧道中观察到的相应值低8％。该研究强调了火车在通过紧密相邻的隧道和较长的隧道运输时空气动力学的差异，得出结论，当火车通过紧密相邻的隧道而不是通过单通道通过时，应考虑改善空气动力学性能。该研究为隧道工程提供了空气动力学的指导和参考。