Flow separation

Flow separation occurs when a fluid flowing over a surface, like air over an airplane wing or water around a car, loses contact with that surface. This happens because the fluid’s movement slows down or changes direction suddenly, causing the smooth flow to break away from the surface. As a result, a wake of turbulent, swirling flow forms behind the object, which can increase drag and reduce efficiency. Flow separation often leads to loss of lift or ability to control the object effectively, and it typically occurs where the surface curves sharply or has abrupt changes in shape.