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− | [[Image:lighterstill.jpg]] [[Image:Vortex_austin.jpg|right]] | + | [[Image:lighterstill.jpg]] [[Image:Vortex_austin.jpg|right|frame]] |
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| A '''vortex''' (pl. ''vortices'') is a [[Rotation|spinning]], often [[Turbulence|turbulent]], | | A '''vortex''' (pl. ''vortices'') is a [[Rotation|spinning]], often [[Turbulence|turbulent]], |
| flow of [[fluid]]. Any [[spiral]] motion with closed [[Streamlines, streaklines and pathlines|streamlines]] is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex. The speed and rate of [[rotation]] of the fluid are greatest at the center, and decrease progressively with distance from the center. | | flow of [[fluid]]. Any [[spiral]] motion with closed [[Streamlines, streaklines and pathlines|streamlines]] is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex. The speed and rate of [[rotation]] of the fluid are greatest at the center, and decrease progressively with distance from the center. |
− | | + | <center>For lessons on the related [[topic]] of '''''[[Portals]]''''', follow [https://nordan.daynal.org/wiki/index.php?title=Category:Portal '''''this link'''''].</center> |
| == Properties == | | == Properties == |
| Vortices display some special properties: | | Vortices display some special properties: |
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| * Two or more vortices that are approximately parallel and circulating in the same direction will quickly merge to form a single vortex. The [[Circulation (fluid dynamics)|circulation]] of the merged vortex will equal the sum of the [[Circulation (fluid dynamics)|circulations]] of the constituent vortices. For example, a sheet of small vortices flows from the trailing edge of the wing or propeller of an airplane when the wing is developing [[Lift (force)|lift]] or the propeller is developing [[thrust]]. In less than one wing [[Chord (aircraft)|chord]] downstream of the trailing edge of the wing these small vortices merge to form a single vortex. If viewed from the tail of the airplane, looking forward in the direction of flight, there is one [[Wingtip vortices|wingtip vortex]] trailing from the left-hand wing and circulating clockwise, and another wingtip vortex trailing from the right-hand wing and circulating anti-clockwise. The result is a region of downwash behind the wing, between the pair of [[wingtip vortices]]. These two [[wingtip vortices]] do not merge because they are circulating in opposite directions. | | * Two or more vortices that are approximately parallel and circulating in the same direction will quickly merge to form a single vortex. The [[Circulation (fluid dynamics)|circulation]] of the merged vortex will equal the sum of the [[Circulation (fluid dynamics)|circulations]] of the constituent vortices. For example, a sheet of small vortices flows from the trailing edge of the wing or propeller of an airplane when the wing is developing [[Lift (force)|lift]] or the propeller is developing [[thrust]]. In less than one wing [[Chord (aircraft)|chord]] downstream of the trailing edge of the wing these small vortices merge to form a single vortex. If viewed from the tail of the airplane, looking forward in the direction of flight, there is one [[Wingtip vortices|wingtip vortex]] trailing from the left-hand wing and circulating clockwise, and another wingtip vortex trailing from the right-hand wing and circulating anti-clockwise. The result is a region of downwash behind the wing, between the pair of [[wingtip vortices]]. These two [[wingtip vortices]] do not merge because they are circulating in opposite directions. |
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− | * Vortices contain a lot of energy in the circular motion of the fluid. In an ideal fluid this energy can never be dissipated and the vortex would persist forever. However, real fluids exhibit [[viscosity]] and this dissipates energy very slowly from the core of the vortex. (See [[Rankine vortex]]). It is only through dissipation of a vortex due to viscosity that a vortex line can end in the fluid, rather than at the boundary of the fluid. For example, the [[wingtip vortices]] from an airplane dissipate slowly and linger in the atmosphere long after the airplane has passed. This is a hazard to other aircraft and is known as [[wake turbulence]].[http://en.wikipedia.org/wiki/Vortex] | + | * Vortices contain a lot of energy in the circular motion of the fluid. In an ideal fluid this energy can never be dissipated and the vortex would persist forever. However, real fluids exhibit [[viscosity]] and this dissipates energy very slowly from the core of the vortex. (See [[Rankine vortex]]). It is only through dissipation of a vortex due to viscosity that a vortex line can end in the fluid, rather than at the boundary of the fluid. For example, the [[wingtip vortices]] from an airplane dissipate slowly and linger in the atmosphere long after the airplane has passed. This is a hazard to other aircraft and is known as [[wake turbulence]].[https://en.wikipedia.org/wiki/Vortex] |
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| [[Category: General Reference]] | | [[Category: General Reference]] |
| [[Category: Physics]] | | [[Category: Physics]] |