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 _    _    __   __   __   __     ___      _____   
| |  | ||  \ \\/ //  \ \\/ //   / _ \\   / ____|| 
| |/\| ||   \ ` //    \   //   / //\ \\ / //---`' 
|  /\  ||    | ||     / . \\  |  ___  ||\ \\___   
|_// \_||    |_||    /_//\_\\ |_||  |_|| \_____|| 
`-`   `-`    `-`'    `-`  --` `-`   `-`   `----`

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Text this: Interactions between circular vortex-rings and free-surfaces