LAUSR

Abstract This paper analyses predictions from Large Eddy Simulations of a section of a double-stacked freight train subjected to various local loading configurations under the influence of cross-wind. In particular, drag, side force and moment coefficients of double-stacked containers on a test wagon were predicted for different combinations of upstream and downstream gaps between neighbouring wagons. The mean flow field around a loaded test wagon was shown to undergo a significant topological change with increasing gap size and yaw angle. The gap range where the drag increases most rapidly was found to change as yaw angle is increased. Various topological changes to the flow over the vehicle were identified using the mean and fluctuating pressure coefficients, and a Proper Orthogonal Decomposition analysis, revealing the dominant flow mechanisms over the roof and at the leeward side of the vehicle, due to the unsteadiness in the flow over those regions. In addition to the fluctuating and extreme aerodynamic side force, the development of mean wake structure with increasing yaw angle are discussed.