Figure 1
Two images show the physical configuration and free-area distribution of a train in a tunnel. Panel a: Physical configuration; train as moving area blockage Atr in tunnel with open portals; friction on tunnel wall and train skin. Panel b: Free-area distribution; A(x,t) from 85.0 to 100.0; tail ramp about 700 to 750, nose ramp about 850 to 900.Quasi-1D representation of the train–tunnel system. (a) Physical configuration: the train is a moving cross-sectional-area blockage in a tunnel with open portals and friction acts both on the tunnel wall and on the train skin in the annular gap. (b) Corresponding free-area distribution A(x, t) actually seen by the solver, plotted from the code, with the cosine nose and tail ramps resolved. Source: Author's own work