boundary layerArticle Free Pass boundary layer, in fluid
mechanics, thin layer of a flowing gas or liquid in contact with
a surface such as that of an airplane wing or of the inside of a
pipe. The fluid in the boundary layer is subjected to shearing
forces. A range of velocities exists across the boundary layer
from maximum to zero, provided the fluid is in contact with the
surface. Boundary layers are thinner at the leading edge of an
aircraft wing and thicker toward the trailing edge. The flow in
such boundary layers is generally laminar at the leading or
upstream portion and turbulent in the trailing or downstream
portion. See also laminar flow; turbulent flow. What made you
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