위키백과

소용돌이: 두 판 사이의 차이

입체적으로 역사 찾아보기
← 이전 편집다음 편집 →
내용 삭제됨 내용 추가됨
시각위키텍스트
편집 요약 없음
7번째 줄:
* 소용돌이는 중심이 움직이는 [[토네이도]]를 의미하며 토네이도는 좌우상하로 움직인다.
 
* 소용돌이의 유체 압력은 중앙에서 최저이다. 그리고 중심에서 멀어질수록 점진적으로 상승한다. 이것은 [[베르누이 원리]]와 일치한다. 공기중의 소용돌이의 핵심은 핵심의 저압내에 응축에의해 유발된 수증기의 플룸 때문에 때때로 보일수 있다.
이것은 [[베르누이 원리]]와 일치한다. 공기중의 소용돌이의 핵심은 핵심의 저압내에 응축에의해 유발된 수증기의 플룸 때문에 때때로 보일수 있다.
<!-- The spout of a [[tornado]] is a classic and frightening example of the visible core of a vortex. A [[dust devil]] is also the core of a vortex, made visible by the dust drawn upwards by the turbulent flow of air from ground level into the low pressure core.
-->
 
* 모든 소용돌이의 핵심은 소용돌이 선을 포함한다고 고려될 수 있고 소용돌이의 모든 입자는 소용돌이 선주위를 회전한다고 고려될 수 있다. 소용돌이 선은 유체의 경계에서 시작하고 끝나지만 유체내에서 시작하거나 끝나지는 않는다.
 
<!--
(See [[Helmholtz's theorems]].) Vortices readily deflect and attach themselves to a solid surface. For example, a vortex usually forms ahead of the [[Propeller|propeller disk]] or [[jet engine]] of a slow-moving [[Fixed-wing aircraft|airplane]]. One end of the vortex line is attached to the propeller disk or jet engine, but when the airplane is taxiing the other end of the vortex line readily attaches itself to the ground rather than end in midair. The vortex can suck water and small stones into the core and then into the propeller disk or jet engine.
-->
* 둘 또는 이상의 소용돌이들이 거의 평행하고 같은 방향으로 회전하면 빠르게 병합되어 하나의 소용돌이가 된다.
<!--
병합된 소용돌이의 순환은 구성 소용돌이의 순환의 합고 같을 것이다.
* 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.
 
-->
* 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]].▼
* 소용돌이는 유체의 원형 움직임내에 많은 에너지를 포함한다. 이상적인 유체에서 이 에너지는 결코 소산될 수 없고 소용돌이는 영원히 지속적일 것이다. 그러나 실제의 유체는 점성을 보이며 이것이 소용돌이의 핵심에서 에너지를 매우 느리게 소산시킬것이다.
 
▲*<!-- 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]].
==Dynamics==
A vortex can be any circular or rotary flow that possesses
30번째 줄:
where <math>\vec \mathit{u}</math> is the ''fluid
velocity''.
=== Free (irrotational) vortex ===▼
 
== Two types of vortex ==
In fluid mechanics, a distinction is often made between two limiting vortex cases. One is called the free (irrotational) vortex, and the other is the forced (rotational) vortex. These are considered as below:
{|
|-
|[[Image:Vortex south.png|thumb|none| Two autumn leaves in a counter-clockwise vortex (reference position).]]
|
|[[Image:Vortex east.png|thumb|none| Two autumn leaves in a rotational vortex rotate with the counter-clockwise flow.]]
|
|[[Image:Free vortex east.png|thumb|none| Two autumn leaves in an irrotational vortex preserve their original orientation while moving counter-clockwise.]]
|}
 
▲=== Free (irrotational) vortex ===
 
When fluid is drawn down a plug-hole, one can observe the phenomenon of a '''free vortex'''. The tangential velocity v varies inversely as the distance r from the center of rotation, so the angular momentum, rv, is constant; the vorticity is zero everywhere (except for a singularity at the center-line) and the [[circulation (fluid dynamics)|circulation]] about a contour containing r=0 has the same value everywhere. The [[free surface]] (if present) dips sharply (as <math>r^{-2}</math> ) as the center line is approached.
원본 주소 "https://ko.wikipedia.org/wiki/소용돌이"