Linked from
The 13 pages that link to Flow separation, each with the reason it gives.
AerodynamicsRelated: Separation can sharply increase drag and reduce lift.
AirfoilRelated: Separation disrupts orderly flow over an airfoil and can sharply reduce lift.
Aerodynamic dragRelated: Separation changes rear pressure and can sharply increase pressure drag.
Dead zoneRelated: Separated flow behind walls or obstacles can enclose slowly exchanging regions.
StreamlineRelated: Streamline plots help locate where attached flow turns away from a surface.
StreamliningRelated: Streamlined shapes delay separation and shrink the wake.
Aircraft fairingRelated: Poorly shaped fairings can trigger separation and increase pressure drag.