With speedup of railways, hydrodynamic phenomena such as vibration or noise have become a significant problem. For further speedup, these phenomena have to be considered to improve comfortability of the ride. It is known that shape of the vehicle affects these phenomena, and in this study, we estimate the effects of rear shape of the vehicle on the flow in terms of pressure coefficient as the preliminary study. We use lattice Boltzmann method and virtual flux method for analyzing the flow around the moving vehicle in a tunnel. As a result, we confirmed that rear shape of the vehicle affects the pressure coefficient on the tunnel wall.