PHAK · Chapter 5: Aerodynamics of Flight
FAA · Retrieved 2026-09-05
Educational reference; original Owl summariesAERODYNAMICS
Boundary layer & separation
FLIGHT SCIENCE / CONCEPT REFERENCE
SCIENCEConditions & principles
The thin region next to a surface where viscosity produces strong velocity gradients.
REFERENCE COVERAGE3 / 3 editorial sections
PROVENANCE1 linked source
LAST RETRIEVED2026-09-05
Editorial section coverage describes the article structure, not scientific validation or completeness.
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Source editions
PHAK · Chapter 5: Aerodynamics of Flight ↗Edition / snapshot: FAA-H-8083-25C, 2023Retrieved: 2026-09-05
Retrieval dates record when Owl obtained the data; they are not publication dates or proof that a specification is current. Where the edition contains only a snapshot date, the original publication date is not recorded.
01
Mechanism
Air at the wall follows the surface motion; velocity changes toward the external flow. An adverse pressure gradient can slow the near-wall air until the flow separates.
02
Aircraft response
Separation increases pressure drag and changes lift and control behavior. Roughness can cause transition and alter the separation pattern.
03
Context & interpretation
A turbulent boundary layer has more mixing and often resists separation better, while typically producing more skin-friction drag than a laminar layer.
Sources & context
Educational explanation of physical mechanisms. Aircraft-specific procedures, limitations and current weather information are separate references.