A computer generated image of model sperm cells suspended in a Stokesian fluid, including the fluid velocity field. All sperm cells swim in the same plane and interact hydrodynamically, leading to visible cluster formation and locally enhanced flows.
Simulated sperm swimming in synchrony —

A computer generated image of model sperm cells suspended in a Stokesian fluid, including the fluid velocity field. All sperm cells swim in the same plane and interact hydrodynamically, leading to visible cluster formation and locally enhanced flows.

https://fluids.ac.uk/pictures/competition/9-sperm_swimming.png