Editing Lift (force) (section)

====Controversy regarding the Coandă effect====
{{Main|Coandă effect}}

Some versions of the flow-deflection explanation of lift cite the Coandă effect as the reason the flow is able to follow the convex upper surface of the airfoil.  The conventional definition in the aerodynamics field is that the ''Coandă effect'' refers to the tendency of a [[Jet (fluid)|fluid jet]] to stay attached to an adjacent surface that curves away from the flow, and the resultant [[Entrainment (hydrodynamics)|entrainment]] of ambient air into the flow.<ref name="auerbach">{{Citation|last=Auerbach|first=David|journal=Eur. J. Phys.|volume=21|issue=4|year=2000|page=289|title=Why Aircraft Fly|doi=10.1088/0143-0807/21/4/302|bibcode=2000EJPh...21..289A|s2cid=250821727 }}</ref><ref>{{Citation|url=http://www.av8n.com/how/htm/spins.html#sec-coanda-fallacy|last=Denker|first=JS|title=Fallacious Model of Lift Production|access-date=18 August 2008|url-status=dead|archive-url=https://web.archive.org/web/20090302153902/http://www.av8n.com/how/htm/spins.html#sec-coanda-fallacy|archive-date=March 2, 2009}}</ref><ref>{{Citation|title=Report on the first European Mechanics Colloquium, on the Coanda effect|last1=Wille|first1=R.|last2=Fernholz|first2=H.|journal=J. Fluid Mech.|year=1965|volume=23|issue=4|page=801|doi=10.1017/S0022112065001702|bibcode=1965JFM....23..801W|s2cid=121981660 }}</ref>

More broadly, some consider the effect to include the tendency of any fluid [[boundary layer]] to adhere to a curved surface, not just the boundary layer accompanying a fluid jet. It is in this broader sense that the Coandă effect is used by some popular references to explain why airflow remains attached to the top side of an airfoil.<ref name="scotteberhart">{{Citation|url=http://www.allstar.fiu.edu/AERO/airflylvl3.htm|last1=Anderson|first1=David|last2=Eberhart|first2=Scott|title=How Airplanes Fly: A Physical Description of Lift|year=1999|access-date=June 4, 2008|url-status=live|archive-url=https://web.archive.org/web/20160126200755/http://www.allstar.fiu.edu/aero/airflylvl3.htm|archive-date=January 26, 2016}}</ref><ref name="raskin">{{Citation|url=http://jef.raskincenter.org/published/coanda_effect.html|archive-url=https://web.archive.org/web/20070928072421/http://jef.raskincenter.org/published/coanda_effect.html|archive-date=September 28, 2007|title=Coanda Effect: Understanding Why Wings Work|last=Raskin|first=Jef|year=1994}}</ref> This is a controversial use of the term "Coandă effect"; the flow following the upper surface simply reflects an absence of boundary-layer separation, thus it is not an example of the Coandă effect.<ref>Auerbach (2000)</ref><ref>Denker (1996)</ref><ref>Wille and Fernholz(1965)</ref><ref>{{citation|last=White|first=Frank M.|title=Fluid Mechanics|year=2002|edition=5th|publisher=McGraw Hill}}</ref> Regardless of whether this broader definition of the "Coandă effect" is applicable, calling it the "Coandă effect" does not provide an explanation, it just gives the phenomenon a name.<ref>McLean, D. (2012), Section 7.3.2</ref>

The ability of a fluid flow to follow a curved path is not dependent on shear forces, viscosity of the fluid, or the presence of a boundary layer. Air flowing around an airfoil, adhering to both upper and lower surfaces, and generating lift, is accepted as a phenomenon in inviscid flow.<ref>McLean, D. (2012), Section 7.3.1.7</ref>