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

  ______    _____    __   __     ___      ______  
 /_   _//  |  ___||  \ \\/ //   / _ \\   /_   _// 
 `-| |,-   | ||__     \   //   / //\ \\    | ||   
   | ||    | ||__     / . \\  |  ___  ||  _| ||   
   |_||    |_____||  /_//\_\\ |_||  |_|| /__//    
   `-`'    `-----`   `-`  --` `-`   `-`  `--`