Detachment of a boundary layer from a surface into a wake
For the repainted ship by Tauba Auerbach, see Flow Separation.
Airflow separating from a wing at a high angle of attack
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake.[1]
A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous forces present in the layer of fluid close to the surface. The flow can be externally, around a body, or internally, in an enclosed passage. Boundary layers can be either laminar or turbulent. A reasonable assessment of whether the boundary layer will be laminar or turbulent can be made by calculating the Reynolds number of the local flow conditions.
Separation occurs in flow that is slowing down, with pressure increasing, after passing the thickest part of a streamline body or passing through a widening passage, for example.
Flowing against an increasing pressure is known as flowing in an adverse pressure gradient. The boundary layer separates when it has travelled far enough in an adverse pressure gradient that the speed of the boundary layer relative to the surface has stopped and reversed direction.[2][3] The flow becomes detached from the surface, and instead takes the forms of eddies and vortices. The fluid exerts a constant pressure on the surface once it has separated instead of a continually increasing pressure if still attached.[4] In aerodynamics, flow separation results in reduced lift and increased pressure drag, caused by the pressure differential between the front and rear surfaces of the object. It causes buffeting of aircraft structures and control surfaces. In internal passages separation causes stalling and vibrations in machinery blading and increased losses (lower efficiency) in inlets and compressors. Much effort and research has gone into the design of aerodynamic and hydrodynamic surface contours and added features which delay flow separation and keep the flow attached for as long as possible. Examples include the fur on a tennis ball, dimples on a golf ball, turbulators on a glider, which induce an early transition to turbulent flow; vortex generators on aircraft.
In fluid dynamics, flowseparation or boundary layer separation is the detachment of a boundary layer from a surface into a wake. A boundary layer exists...
FlowSeparation is a red and white, marbled repainting of the John J. Harvey fireboat by artist Tauba Auerbach. The project was a collaboration with the...
from the surface of the object. At very low Reynolds numbers, without flowseparation, the drag force F d {\displaystyle F_{\mathrm {d} }} is proportional...
Claire E.; Marshall, David P. (2001). "Flow past a Cylinder on a Plane, with Application to Gulf Stream Separation and the Antarctic Circumpolar Current"...
fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics...
engine power. Positive stalling Flowseparation occur on the suction side of the blade. Negative stalling Flowseparation occur on the pressure side of...
Look up separation in Wiktionary, the free dictionary. Wikiquote has quotations related to Separation. Separation may refer to: Separation (1967 film)...
even become reversed causing a flowseparation. This has very significant consequences in aerodynamics since flowseparation significantly modifies the pressure...
methods of controlling the behaviour of fluid flow boundary layers. It may be desirable to reduce flowseparation on fast vehicles to reduce the size of the...
high-speed flow control using localized arc filament plasma actuators, and low-speed flow control using dielectric barrier discharges for flowseparation and...
by assuming inviscid flow and investigating the irrotational flow pattern around the solid body. Real fluids experience separation of the boundary layer...
Cyclonic separation is a method of removing particulates from an air, gas or liquid stream, without the use of filters, through vortex separation. When removing...
sufficiently high angle the wing exhibits flowseparation, together with an associated high drag. Ordinarily, this flowseparation leads to a loss of lift known as...
slow-moving boundary layer in contact with the airfoil surface, delays local flowseparation and aerodynamic stalling, thereby improving the effectiveness of wings...
exit pressure is less than approximately 40% that of ambient, then "flowseparation" occurs. This can cause exhaust instabilities that can cause damage...
other structures, such as boundary layers, to produce new flow structures such as flowseparation, transition, etc. Blast wave Shock waves in astrophysics...
where the jet is more or less horizontal. The effect is also observed in flow from a tank into a pipe, or a sudden contraction in pipe diameter. Streamlines...
turbulence generated by the air flow around a tall building: the energy-containing eddies generated by flowseparation have sizes of the order of tens...
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trailing edge. This shock causes transonic wave drag and can induce flowseparation behind it; both have negative effects on the airfoil's performance...
on the helmet can cause considerable neck strain on the driver, and flowseparation on the back side of the helmet can cause turbulent buffeting and thus...
Field-flow fractionation, abbreviated FFF, is a separation technique invented by J. Calvin Giddings. The technique is based on separation of colloidal...
information can only flow from one machine to another along known external communication lines. One of the properties we must prove of a separation kernel, therefore...
performance. Flow at the intake and its turning from axial to radial direction causes losses at the intake. Friction and flowseparation cause impeller...
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