Non-Newtonian fluid

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Non-Newtonian fluid

A non-Newtonian fluid is a fluid

Fluid

A fluid is defined as a substance that continually deforms under an applied shear stress. All liquids and all gases are fluids. Fluids are a subset of the Phase and include liquids, gas, Plasma physics and, to some extent, plasticity ....
whose flow properties are not described by a single constant value of viscosity

Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
. Many polymer

Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
solutions and molten polymers are non-Newtonian fluids, as are many commonly found substances such as ketchup

Ketchup

Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
suspensions, paint

Paint

Paint is any liquid, liquifiable, or mastic composition which after application to a Substrate in a thin layer is converted to an opaque solid film....
, blood

Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
and shampoo

Shampoo

Shampoo is a hair care product used for the removal of sebum, dirt, skin particles, dandruff, environmental pollutants and other contaminant particles that gradually build up in hair....
. In a Newtonian fluid, the relation between the shear stress

Shear stress

File:Shear stress.JPGA shear stress, denoted , is defined as a stress which is applied parallel or tangent to a face of a material, as opposed to a normal stress which is applied perpendicularly....
and the strain rate

Strain rate

Origin (mathematics)

In mathematics, the origin of a Euclidean space is a special Point , usually denoted by the letter O, used as a fixed point of reference for the geometry of the surrounding space....
), the constant of proportionality being the coefficient of viscosity

Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
.

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Encyclopedia

A non-Newtonian fluid is a fluid

Fluid

Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
. Many polymer

Polymer

Ketchup

Starch

Paint

Paint is any liquid, liquifiable, or mastic composition which after application to a Substrate in a thin layer is converted to an opaque solid film....
, blood

Blood

Shampoo

Shear stress

Strain rate

Origin (mathematics)

Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
. In a non-Newtonian fluid, the relation between the shear stress

Shear stress

Strain rate

Strain rate, with regards to materials science, is the change in Strain over the change in time and is denoted as ?.? = de/dtWe havewhere is the original length and is the speed of deformation....
is nonlinear, and can even be time-dependent. Therefore a constant coefficient of viscosity can not be defined. A ratio between shear stress and rate of strain (or shear-dependent viscosity) can be defined, this concept being more useful for fluids without time-dependent behavior.

Although the concept of viscosity is commonly used to characterize a material, it can be inadequate to describe the mechanical behavior of a substance, particularly non-Newtonian fluids. They are best studied through several other rheological

Rheology

Rheology is the study of the flow of matter: mainly liquids but also soft solids or solids under conditions in which they flow rather than deform elastically....
properties which relate the relations between the stress

Stress (physics)

In continuum mechanics, stress is a measure of the average amount of force exerted per unit area. It is a measure of the intensity of the total internal forces acting within a body across imaginary internal surfaces, as a reaction to external applied forces and body forces....
and strain rate

Strain rate

Oscillation

Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and Alternating current power....
shear, or extensional flow which are measured using different devices or rheometers. The properties are better studied using tensor

Tensor

A tensor is an object which extends the notion of Scalar , Vector , and Matrix . The term has slightly different meanings in mathematics and physics....
-valued constitutive equations, which are common in the field of continuum mechanics

Continuum mechanics

Continuum mechanics is a branch of mechanics that deals with the analysis of the kinematics and mechanical behavior of materials modeled as a continuum, e.g., solids and fluids ....
.

Common examples

An inexpensive, non-toxic

Toxicity

Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver ....
example of a non-Newtonian fluid is a suspension of starch ( flour) in water, sometimes called oobleck

Oobleck

Oobleck is a fictional green precipitation invented by children's author Dr. Seuss in the book Bartholomew and the Oobleck. The word has since been used to describe a mixture of corn starch and water used to demonstrate the dilatant property of non-Newtonian fluids....
(uncooked imitation custard

Bird's Custard

Bird's Custard is the original version of what is known generically as custard powder. It is cornstarch-based, and thickens to form a custard-like sauce when mixed with milk and heated to a sufficient temperature....
, being a suspension of primarily corn flour, has the same properties). The application of force

Force

In physics, a force is that which can cause an object with mass to change its velocity. Force has both Euclidean_vector#Length of a vector and Direction , making it a Vector quantity....
— for example by stabbing the surface with a finger, or rapidly inverting the container holding it — leads to the fluid behaving like a solid

Solid

A solid object is in the states of matter characterized by resistance to deformation and changes of volume. In other words, it has high values both of Young's modulus and of shear modulus; this contrasts e.g....
rather than a liquid. This is the "shear thickening" property of this non-Newtonian fluid. More gentle treatment, such as slowly inserting a spoon, will leave it in its liquid state. Trying to jerk the spoon back out again, however, will trigger the return of the temporary solid state. A person moving quickly and applying sufficient force with their feet can literally walk across such a liquid.

Shear thickening fluids

Dilatant

A dilatant material is one in which viscosity increases with the rate of shear stress. Such a shear thickening fluid, also known by the acronym STF, is an example of a non-Newtonian fluid....
of this sort are being researched for bullet resistant body armor, useful for their ability to absorb the energy of a high velocity projectile impact but remain soft and flexible while worn. Some shear thickening fluids are also used in all wheel drive systems utilising a viscous coupling unit

Viscous coupling unit

A viscous coupling is made up of alternating circular plates. The plates have tabs or perforations in them. The plates are mounted in a sealed drum, and are located very close to each other....
for power transmission.

A familiar example of the opposite, a shear thinning fluid

Shear thinning

A pseudoplastic material is one in which viscosity decreases with increasing rate of shear stress . This property is found in certain complex solutions, such as ketchup, whipped cream, blood, paint, and nail polish....
, or pseudoplastic fluid, is paint

Paint

Paint is any liquid, liquifiable, or mastic composition which after application to a Substrate in a thin layer is converted to an opaque solid film....
: one wants the paint to flow readily off the brush when it is being applied to the surface being painted, but not to drip excessively.

There are fluids which have a linear shear stress, shear strain relationship, that requires a finite yield stress before they begin to flow. That is the shear stress, shear strain curve doesn't pass through the origin. These fluids are called Bingham plastic

Bingham plastic

A Bingham plastic is a viscoplastic material that behaves as a rigid body at low stresses but flows as a viscosity fluid at high stress. It is named after Eugene C....
s. Several examples are clay suspensions, drilling mud, toothpaste, mayonnaise, chocolate, and mustard. The classic case is ketchup

Ketchup

Ketchup, also known as tomato ketchup, tomato sauce, red sauce is a condiment, usually made from tomatoes. The primary ingredients in a typical modern ketchup are tomato concentrate, spirit vinegar, milk, corn syrup, or other sugar, edible salt, spice and herb extracts , spice and garlic powder....
which will not come out of the bottle until you stress it by shaking.

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).

Classification types

Kelvin material	"Parallel" linear combination of elastic and viscous effects
Anelastic Viscoelasticity Viscoelasticity is the property of materials that exhibit both Viscosity and Elasticity characteristics when undergoing Deformation. Viscous materials, like honey, resist shear flow and Strain linearly with time when a Stress is applied....	Material returns to a well-defined "rest shape"
Time-dependent viscosity	Rheopectic Rheopecty Rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shearing force, the higher its viscosity....	Apparent viscosity Viscosity Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness".... increases with duration of stress	Some lubricant Lubricant A lubricant is a substance introduced between two moving surfaces to reduce the friction between them, improving efficiency and reducing wear.... s
Time-dependent viscosity	Thixotropic Thixotropy Thixotropy is the property of some Non-Newtonian fluid Power-law fluid fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower is its viscosity....	Apparent viscosity Viscosity Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness".... decreases with duration of stress	Some Clays, Some Drilling Mud Drilling mud In geotechnical engineering, drilling mud, also known as spud mud , is a drilling fluid used to drill boreholes into the earth. Often used while drilling oil well and natural gas wells and on exploration drilling rigs but can also be used for much simpler boreholes, such as water wells.... , synovial fluid Synovial fluid Synovial fluid is a thick, stringy fluid found in the cavities of synovial joints. With its egg-like consistency , synovial fluid reduces friction between the articular cartilage and other tissues in joints to lubricate and cushion them during movement.... , Honey Honey Honey is a sweet fluid produced by honey bees , and derived from the nectar of flowers. According to the United States National Honey Board and various international food regulations, "honey stipulates a pure product that does not allow for the addition of any other substance?this includes, but is not limited to, water or other sweeteners... under certain conditions
Shear-stress-dependent viscosity	Dilatant Dilatant A dilatant material is one in which viscosity increases with the rate of shear stress. Such a shear thickening fluid, also known by the acronym STF, is an example of a non-Newtonian fluid....	Apparent viscosity Viscosity Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness".... increases with increased stress	Suspensions of corn starch or sand in water Quicksand Quicksand is a colloid hydrogel consisting of fine granular matter , clay, and brine. In the name, as in that of Mercury , "quick" does not mean "fast," but "living" ....
Shear-stress-dependent viscosity	Pseudoplastic	Apparent viscosity Viscosity Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness".... decreases with increased stress	Paper pulp in water, latex paint, blood plasma, syrup, molasses
Generalized Newtonian fluid Generalized Newtonian fluid A generalized Newtonian fluid is an idealized fluid for which the shear stress, τ, is a function of shear rate at the particular time, but not dependent upon the history of deformation.... s		Stress depends on normal and shear strain rates and also the pressure applied on it	Blood Blood Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells.... , Custard Custard Custard is a range of preparations based on milk and Egg s, thickened with heat. Most commonly, custard refers to a dessert or dessert sauce, but custard bases are also used for quiches and other savoury foods....

Non-Newtonian fluid

Common examples

Classification types

See also