How do eddies form?

Eddies form when fluid flows over obstacles or through varying terrain, creating localized whirlpools or circular currents. These disturbances can result from changes in velocity, pressure, or direction of the main flow, leading to the separation of the fluid layers. In oceans and rivers, eddies can also arise from turbulence, where chaotic fluid motions generate rotating pockets of water. These features play a crucial role in mixing and transporting energy and nutrients in aquatic environments.