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"/> It can be defined as the flow of a fluid around a body that is completely submerged in it. Examples include 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]], water flowing around submarines, and air flowing around a truck;<ref name="truck"/> a 2000 paper analyzing the latter 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"/>

{{Multiple issues|{{underlinked|date=November 2012}}|unreferenced = January 2007|orphan = November 2009}}

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 [[fluid mechanics]], '''external flow''' is such a flow that boundary layers develop freely, without constraints imposed by adjacent surfaces. Accordingly, there will always exist a region of the flow outside the boundary layer in which velocity, temperature, and/or concentration gradients are negligible.It can be defined as the flow of a fluid around a body that is completely submerged in it.

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="AIP"/>

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.

==References==

<references>

<ref name="AIP">

{{Cite journal

| last1 = Jendoubi | first1 = S.

| last2 = Strykowski | first2 = P. J.

| date = September 1, 1994

| 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>

{{DEFAULTSORT:External Flow}}

[[Category:Aerodynamics]]

[[Category:FluidFlow dynamicsregimes]]

{{Fluiddynamics-stub}}