Boundary Layer

In physics and fluid mechanics, a boundary layer is the layer of fluid in the immediate vicinity of a bounding surface where the effects of viscosity are significant. In the Earth's atmosphere, the planetary boundary layer is the air layer near the ground affected by diurnal heat, moisture or momentum transfer to or from the surface. On an aircraft wing the boundary layer is the part of the flow close to the wing, where viscous forces distort the surrounding non-viscous flow. See Reynolds number.

Laminar boundary layers can be loosely classified according to their structure and the circumstances under which they are created. The thin shear layer which develops on an oscillating body is an example of a Stokes boundary layer, while the Blasius boundary layer refers to the well-known similarity solution near an attached flat plate held in an oncoming unidirectional flow. When a fluid rotates and viscous forces are balanced by the Coriolis effect (rather than convective inertia), an Ekman layer forms. In the theory of heat transfer, a thermal boundary layer occurs. A surface can have multiple types of boundary layer simultaneously.

Read more about Boundary LayerAerodynamics, Naval Architecture, Boundary Layer Equations, Turbulent Boundary Layers, Heat and Mass Transfer, Boundary Layer Turbine

Other articles related to "boundary layer, layer, boundary layers":

Lifted Condensation Level - Relation With CCL
... surface air and subsequent mixing of the planetary boundary layer, so that the layer near the surface ends up with a dry adiabatic lapse rate ... solar heating of the surface will cause a cloud to form topping the well-mixed boundary layer, and the level at which this occurs is called the CCL ... If the boundary layer starts off with a stable temperature profile (that is, with a lapse rate less than the dry adiabatic lapse rate), then the CCL will be ...
Examples of Secondary Flows - Circular Flow in A Bowl or Cup
... The pressure gradient also accounts for a secondary flow of the boundary layer in the water flowing across the floor of the bowl or cup ... The slower speed of the water in the boundary layer is unable to balance the pressure gradient ... The boundary layer spirals inward toward the axis of circulation of the water ...
Leading Edge Slats - Operation
... work by inducing a high energy stream to the flow of the main airfoil thus re-energizing its boundary layer and delaying stall ... it cannot be called high-energy air since all the air outside the actual boundary layers has the same total heat ... Fresh boundary layer effect Each new element starts out with a fresh boundary layer at its leading edge ...
Boundary Layer Turbine
... to as a bladeless turbine because it uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine ... Boundary layer turbines are also known as cohesion-type turbine, bladeless turbine, and Prandtl layer turbine (after Ludwig Prandtl) ...
Stokes Boundary Layer
... In fluid dynamics, the Stokes boundary layer, or oscillatory boundary layer, refers to the boundary layer close to a solid wall in oscillatory flow of a viscous fluid ... a smooth solid wall, George Gabriel Stokes – after whom this boundary layer is called – derived an analytic solution, one of the few exact ... In turbulent flow, this is still named a Stokes boundary layer, but now one has to rely on experiments, numerical simulations or approximate methods in order to obtain ...

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