CFD Simulation of the Flow over a Train Entering a Tunnel

The solution of the airflow over a train entering a tunnel can be difficult to solve and traditional approaches include ALE techniques and contact surfaces. Here the problem was solved using a novel moving boundary condition approach. In this problem, the train and tunnel are two solid bodies moving relative to each other. To solve the problem the reference frame and finite element mesh are fixed with respect to the train. The effect of the tunnel can then be moved through the mesh at the train speed. The moving boundary condition at the tunnel solid boundary is set to satisfy the velocity conditions as well as satisfying the continuity and momentum equations.

The purpose of the study was to predict the pressures and forces on a high speed train entering a tunnel. The problem solved is a train and tunnel geometry modeled with some detail including features such as the rails. The train speed in the problem is 70 m/s and the pressures and forces were calculated using a incompressible invisid flow solver. The calculated pressures on the train and tunnel surfaces are shown in Figure 1. These pressures were integrated over the train car surfaces to calculate the resultant lift, yaw, and drag forces.

For inquiries or comments, please contact:
Robert MacNeill
Principal Engineer
e-mail: rmacneill@ara.com