boundary-layer separation

boundary-layer separation

[′bau̇n·drē ‚lā·ər sep·ə′rā·shən]
(fluid mechanics)
That point where the boundary layer no longer continues to follow the contour of the boundary because the residual momentum of the fluid (left after overcoming viscous forces) may be insufficient to allow the flow to proceed into regions of increasing pressure. Also known as flow separation.

boundary-layer separation

boundary-layer separationclick for a larger image
A separation of the boundary layer from the boundary surface, resulting in turbulence.