The region where the turbulent flow touches the surface again is called reattachment point. The volume enclosed by the regions of separated laminar flow and turbulent flow is called a laminar separation bubble. Inside the bubble the flow may be circulating, the direction near the airfoil surface may even be the opposite of the direction of the outer flow. There is almost no energy exchange with the outer flow, which makes the laminar separation bubble quite stable. Laminar flow, separation bubble and turbulent flow.