10.1371/journal.pone.0189798.g007 Lirong Jia Lirong Jia Dan Zhou Dan Zhou Jiqiang Niu Jiqiang Niu Instantaneous iso-surface plot of Q-criteria colored by mean velocity (Q = 50000). Public Library of Science 2017 DDES side surface pressure 8 cars surface pressure boundary layer train length influences tail car train length increases friction drag coefficient drag coefficient wind tunnel test train length 3 cars 2017-12-19 18:30:55 Figure https://plos.figshare.com/articles/figure/Instantaneous_iso-surface_plot_of_Q-criteria_colored_by_mean_velocity_Q_50000_/5717446 <p>Instantaneous iso-surface plot of Q-criteria colored by mean velocity (Q = 50000).</p>