Aerodynamics plays a crucial role in the design and development of high-speed trains from the point of
view of cost effectiveness, safety, comfort, and minimal impact on the environment, amongst many other
factors. Train-tunnel interaction create pressure transients which may threaten the structural integrity
of the trains and may also cause some discomfort to the passengers.
A three dimensional numerical simulation is performed to investigate the unsteady compressible turbulent
flow induced by a practical train passing through a single-track tunnel having an entrance and an exit
using a modified KIVA-3 code. The train is treated as solid object, which moves through the mesh using the
modified snapper technique. The experimental results of a projectile shooting into a pipe are used to
validate the modified code and compared well with the computational data, especially in the period of the
projectile entry, which shows the code can be used to predict the pressure fluctuations of train-tunnel
In an attempt to better understand the aerodynamic phenomena peculiar to the train-tunnel interaction,
the formation and propagation of the pressure waves, the radiation and reflection of the waves at the
tunnel portals and the histories of aerodynamic forces on the train are discussed. It is known the speed of
the train plays a dominant role in determining the pattern of pressure histories in the train-tunnel
system. Accordingly, the flow field with the proper shorter train/tunnel can be assumed to mirror the main
features of the real train-tunnel interaction, which is of significant for the three-dimensional simulation.