# Does turbulent flow have boundary layer ? Does separated flow have boundary layer?

I have a little confusion between turbulent flow and separated flow. Consider a flow over a typical airfoil: Does turbulent flow region have boundary layer ? Does separated flow region have boundary layer ?

• The boundary layer is the volume between null airspeed surface and ambient airspeed surface. The null airspeed at some point stops being bound to the wing surface, at the surface the flow is reversed. The boundary layer still follows the null airspeed surface (source). So the boundary layer looks a bit like this (there is a mistake in the exact location, but this is the idea) – mins Sep 30 '17 at 18:39