Exploring the Flow Around a Generic High-Speed Train Under the Influence of Side Winds Using LES

Paper in proceeding, 2006

Large-eddy simulation (LES) is made of the flow around a generic train model at two different yaw angles of 90 degree and 35 degree. The Reynolds number, based on the freestream velocity and the height of the train, is 300000 and 370000 for the yaw angles of 90 and 35 degrees, respectively. Both the time-averaged and instantaneous flows are explored. The LES results show that the influence of the three-dimensional flow from the nose of the train on the time-averaged wake flow at the 90 yaw angle is limited to a region of a length of 3.5 train heights from the tip of the nose in the direction of the length of the train. The instantaneous flow shows an unsteady vortex shedding due to the shear layer instabilities on the periphery of the recirculation region and the exterior flow. Weak vortex shedding is found in the case of the 35 yaw angle. Instead, unstable vortices are found in the wake flow. These vortices detach from and reattach to the train surface in a regular fashion leaving disturbances on the train surface and hence affecting the aerodynamic coefficients.