Editing Non-Newtonian fluid (section)

==Types of non-Newtonian behavior==

===Summary===
[[File:Rheology of time independent fluids.svg|thumb|right|alt=Graph of shear stress (vertical axis) against shear rate (horizontal axis). Three lines extend straight up and to the right from the origin: Newtonian (straight), pseudoplastic (bending down) and dilatant (bending up). Two others extend from a point on the vertical axis above the origin: Bingham plastic (straight) and Bingham pseudoplastic (bending down). |Classification of fluids with shear stress as a function of shear rate. The gradient of each line represents the material's viscosity at the given shear rate.]]

{| class="wikitable"
|+Comparison of non-Newtonian, Newtonian, and viscoelastic properties
! Behaviour
! Models
! Properties
! Examples
|-
|rowspan=1|[[Viscoelastic]]
|[[Kelvin material]], [[Maxwell material]]
|"Parallel" linear combination of elastic and viscous effects<ref name=springer2>{{cite book| title=Springer handbook of experimental fluid mechanics |first1=Cameron |last1=Tropea |first2=Alexander L. |last2=Yarin |first3=John F. |last3=Foss |publisher=Springer |year=2007 |isbn=978-3-540-25141-5 |pages=661, 676 |url=https://books.google.com/books?id=y0xDUAdQAlkC&q=thixotropic&pg=PA667}}</ref>
|Some [[lubricant]]s, [[whipped cream]], [[Silly Putty]]
|-
|rowspan=2|[[Time-dependent viscosity]]
|[[Rheopecty|Rheopectic]]
|[[Apparent viscosity]] increases with duration of stress
|[[Synovial fluid]], [[printer ink]], [[gypsum]] paste
|-
|[[Thixotropy|Thixotropic]]
|Apparent viscosity decreases with duration of stress<ref name=springer2/>
|[[Yogurt]], [[peanut butter]], [[xanthan gum]] solutions, aqueous [[iron oxide]] gels, [[gelatin]] gels, [[pectin]] gels, [[castor wax|hydrogenated castor oil]], some [[clay]]s (including [[bentonite]], and [[montmorillonite]]), [[carbon black]] suspension in molten tire rubber, some [[drilling mud]]s, many [[paint]]s, many [[Flocculant|floc]] suspensions, many [[colloid]]al suspensions
|-
|rowspan=3|Non-Newtonian viscosity
|[[Shear thickening]] (dilatant)
|Apparent viscosity increases with increased stress<ref name=padb/>
|Suspensions of [[corn starch]] in water (oobleck)
|-
|[[Shear thinning]] (pseudoplastic)
|Apparent viscosity decreases with increased stress<ref>{{cite book|title=Rheology of Fluid and Semisolid Foods: Principles and Applications |first=M. A. |last=Rao |publisher=Springer |edition=2nd|year=2007 |isbn=978-0-387-70929-1 |page=8 |url=https://books.google.com/books?id=BLlmimePW18C&q=%22shear+thinning%22&pg=PA8}}</ref><ref>{{cite book| title=Emulsions, Foams, and Suspensions: Fundamentals and Applications |first=Laurier L. |last=Schramm |publisher=Wiley VCH |year=2005 |isbn=978-3-527-30743-2 |page=173 |url=https://books.google.com/books?id=qFi61f1NqNIC&q=pseudoplastic&pg=PA173}}</ref>
|[[Nail polish]], [[whipped cream]], [[ketchup]], [[molasses]], syrups, paper pulp in water, [[Acrylic paint|latex paint]], [[ice sheet dynamics|ice]], [[blood]], some [[silicone oil]]s, some [[silicone resin|silicone coatings]], [[quicksand|sand in water]]
|-
|-
|colspan=1|[[Generalized Newtonian fluid]]s
|Viscosity is function of the shear strain rate.<br />Stress depends on normal and shear strain rates and also the pressure applied on it
|[[Blood plasma]], [[custard]], [[water]]
|}

===Shear thickening fluid===
The viscosity of a shear thickening{{snd}}i.e. [[dilatant]]{{snd}} fluid appears to increase when the shear rate increases. [[Corn starch]] suspended in water ("oobleck", see [[#Oobleck|below]]) is a common example: when stirred slowly it looks milky, when stirred vigorously it feels like a very viscous liquid.

===Shear thinning fluid===
[[File:Painting with non-newtonian fluid.jpg|left|thumb|Paint is a non-Newtonian fluid. A flat surface covered with white paint is oriented vertically (before taking the picture the flat surface was horizontal, placed on a table). The fluid starts dripping down the surface but, because of its non-Newtonian nature, it is subjected to stress due to the [[gravitational acceleration]]. Therefore, instead of slipping along the surface, it forms very large and very dense droplets with limited dripping.]]

A familiar example of the opposite, a [[Shear thinning|shear thinning fluid]], or pseudoplastic fluid, is wall [[paint]]: The paint should flow readily off the brush when it is being applied to a surface but not drip excessively. Note that all [[Thixotropy|thixotropic]] fluids are extremely shear thinning, but they are significantly time dependent, whereas the colloidal "shear thinning" fluids respond instantaneously to changes in shear rate. Thus, to avoid confusion, the latter classification is more clearly termed pseudoplastic.

Another example of a shear thinning fluid is blood. This application is highly favoured within the body, as it allows the viscosity of blood to decrease with increased shear strain rate.

===Bingham plastic===
Fluids that have a linear shear stress/shear strain relationship but require a finite yield stress before they begin to flow (the plot of shear stress against shear strain does not pass through the origin) are called [[Bingham plastic]]s. Several examples are clay suspensions, drilling mud, toothpaste, mayonnaise, chocolate, and mustard. The surface of a Bingham plastic can hold peaks when it is still. By contrast [[Newtonian fluid|Newtonian]] fluids have flat featureless surfaces when still.

===Rheopectic or anti-thixotropic===
There are also fluids whose strain rate is a function of time. Fluids that require a gradually increasing shear stress to maintain a constant strain rate are referred to as [[rheopectic]]. An opposite case of this is a fluid that thins out with time and requires a decreasing stress to maintain a constant strain rate ([[thixotropic]]).