Supercooled Large Droplet (SLD)

 Under SLD conditions, due to the large size of droplets, physical phenomena such as wall-droplet interaction and deformation have a significant effect on the icing process. This causes that the existing icing code cannot predict accurately the ice shapes on the surfaces. To solve this problem, impingement areas were divided into 3 different regions, and the post-processing method was introduced with the new wall-droplet interaction model. In order to consider the effect of deformation, the most suitable model was selected by comparing the deformation models used in the various icing codes. The results showed improved accurately in predicting the collection efficiency.

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• Figure 1. Post-breakup droplets

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• Figure 2. Droplet-wall interactions

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• Figure 3. Droplet impingement (Rime case)

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• Figure 4. Droplet impingement (Glaze case)

Snow Saltation

 The accumulation of snow on a train bogie hinders the smooth operation of important pats, such as brake calipers and dampers, degrading the safety of the vehicle. This is primarily due to snow saltation from the ground owing to the strong winds generated by high-speed trains. To understand the mechanism of snow accretion on a train, simulation studies analyzed train models comprising eight cars. The process of snow saltation was described by implementing the semi-empirical model into a boundary condition. Additionally, we adopted the Eulerian method for computational efficiency. The results showed an increasing trend in the snow accretion toward the rear of the train owing to the snow saltation caused by the wind.

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• Figure 1. Impinging mass flux of snow on a train

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• Figure 2. Snow saltation region

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• Figure 3. Tranport rate of snow saltation