Two-dimensional simulation of a swimmer performing a C-start maneuvering. Colors indicate positive (red) and negative (blue) vorticity, while grey edges represent the Lagrangian coherent structures generated by the moving body. The fish "rolls up a ball" in the C shape and with a backflip of the tail it sheds it downstream, gaining momentum in the opposite direction.
1) M. Gazzola, W. van Rees, and P. Koumoutsakos. C-start: optimal start of larval fish. Journal of Fluid Mechanics, 698:5–18, 2012.