External flow: Difference between revisions

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In [[fluid mechanics]], '''external flow''' is a flow that [[boundary layer]]s develop freely, without constraints imposed by adjacent surfaces.<ref name="AIP"/><ref name="dynamics"/> Accordingly, there will always exist a region of the flow outside the boundary layer in which velocity, temperature, and/or [[concentration gradient]]s are negligible. It can be defined as the flow of a fluid around a body that is completely submerged in it. AnExamples example includesinclude fluid motion over a flat plate (inclined or parallel to the free stream velocity) and flow over curved surfaces such as a sphere, cylinder, [[airfoil]], or [[turbine blade]], airwater flowing around an airplanesubmarines, and waterair flowing around a truck;<ref name="truck"/> a 2000 paper analyzing the submarineslatter used [[computational fluid dynamics]] to model the three-dimensional flow structure and pressure distribution on the external surface of the truck.<ref name="truck"/> In a 2008 paper, external flow was said to be "arguably is the most common and best studied case in [[soft matter]] systems.<ref name="stochastic"/>

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{{unreferenced|date=January 2007}}

In [[fluid mechanics]], '''external flow''' is a flow that [[boundary layer]]s develop freely, without constraints imposed by adjacent surfaces.<ref name="AIP"/><ref name="dynamics"/> Accordingly, there will always exist a region of the flow outside the boundary layer in which velocity, temperature, and/or [[concentration gradient]]s are negligible. It can be defined as the flow of a fluid around a body that is completely submerged in it. An example includes fluid motion over a flat plate (inclined or parallel to the free stream velocity) and flow over curved surfaces such as a sphere, cylinder, [[airfoil]], or [[turbine blade]], air flowing around an airplane and water flowing around the submarines.

The term can also be used simply to describe flow in any body of fluid external to the system under consideration.<ref name="external"/><ref name="asme"/>

In external co-flow, fluid in the external region occurs in the same direction as flow within the system of interest; this contrasts with external counterflow.<ref name="absoluteAIP"/>

==References==

<references>

<ref name="AIP">https://aip.scitation.org/doi/abs/10.1063/1.868126</ref>

{{Cite journal

<ref name="dynamics">https://arxiv.org/abs/cond-mat/0702650</ref>

| last1 = Jendoubi | first1 = S.

<ref name="external">https://www.sciencedirect.com/science/article/abs/pii/S0167610506000857</ref>

| last2 = Strykowski | first2 = P. J.

<ref name="absolute">https://aip.scitation.org/doi/abs/10.1063/1.868126</ref>

| date = September 1, 1994

<ref name="asme">https://asmedigitalcollection.asme.org/GT/proceedings/GT1994/78835/V001T01A041/255325</ref>

| title = Absolute and convective instability of axisymmetric jets with external flow

| journal = Physics of Fluids

| volume = 6 | issue = 9 | pages = 3000–3009

| bibcode = 1994PhFl....6.3000J

| doi = 10.1063/1.868126

}}</ref>

<ref name="dynamics">

{{Cite journal

| last1 = Lebedev | first1 = V. V.

| last2 = Turitsyn | first2 = K. S.

| last3 = Vergeles | first3 = S. S.

| date = November 20, 2007

| title = Dynamics of nearly spherical vesicles in an external flow

| journal = Physical Review Letters

| volume = 99 | issue = 21 | pages = 218101

| arxiv = cond-mat/0702650

| bibcode = 2007PhRvL..99u8101L

| doi = 10.1103/PhysRevLett.99.218101

| pmid = 18233260

| s2cid = 17517230

}}</ref>

<ref name="external">

{{Cite journal

| last1 = Chiu | first1 = Y-H.

| last2 = Etheridge | first2 = D. W.

| date = April 1, 2007

| title = External flow effects on the discharge coefficients of two types of ventilation opening

| journal = Journal of Wind Engineering and Industrial Aerodynamics

| volume = 95 | issue = 4 | pages = 225–252

| doi = 10.1016/j.jweia.2006.06.013

| bibcode = 2007JWEIA..95..225C

}}</ref>

<ref name="asme">

{{Cite book

| last1 = Chew | first1 = J. W.

| last2 = Green | first2 = T.

| last3 = Turner | first3 = A. B.

| date = February 18, 2015

| chapter = Rim Sealing of Rotor-Stator Wheelspaces in the Presence of External Flow

| title = Turbo Expo: Power for Land, Sea, and Air

| publisher = American Society of Mechanical Engineers

| doi = 10.1115/94-GT-126

| isbn = 978-0-7918-7883-5

| s2cid = 110218328

}}</ref>

<ref name="stochastic">

{{Cite journal

| last1 = Speck | first1 = Thomas

| last2 = Mehl | first2 = Jakob

| last3 = Seifert | first3 = Udo

| date = April 28, 2008

| title = Role of External Flow and Frame Invariance in Stochastic Thermodynamics

| journal = Physical Review Letters

| volume = 100 | issue = 17 | pages = 178302

| arxiv = 0712.0232

| bibcode = 2008PhRvL.100q8302S

| doi = 10.1103/PhysRevLett.100.178302

| pmid = 18518344

| s2cid = 2743850

}}</ref>

<ref name="truck">

{{Cite journal

| last1 = Roy |first1=Subrata

| last2 = Srinivasan |first2=Pradeep

| year = 2000

| title = External Flow Analysis of a Truck for Drag Reduction

| journal = SAE Transactions

| volume = 109 | pages = 808–812

| jstor = 44650820

}}</ref>

</references>