Monthly Archive for March, 2017

Train Aerodynamics (part 1)

The metro trains experience an interesting set of aerodynamic effects in the tunnels. The train itself is used to circulate air through the tunnels and ventilation systems (hence its shape is not very aerodynamic at all, not that it matters at these low speeds). Of course, the main aerodynamic effect on the train is the drag force. On long sloped down sections of track (where the train moves without any power input) the aerodynamic drag can provide about 5 km/h of speed difference as train accelerates from 30 km/h to 80 km/h.

For Subtransit, I’m working on an aerodynamic model that would account for both drag produced by the train as it moves through the tunnel as well as additional torque force produced when train passes by a ventilation shaft. Currently, the CFD results are only preliminary, although there are a few interesting results already.

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General Teaser Info

I wanted to make a kind of a general post about the teaser video we presented when announcing Subtransit. The train in this video is running on a pre-determined sequence of events – but otherwise everything is physically simulated. The only thing that was fully animated in the video was the camera movement (which I keyed in manually with the curves editor).

The teaser video takes place on a section of the Moscow Circle line, track 1. This section is one of many that make up the entire big level (each section is streamed in as player moves around the level).

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