Non-Newtonian fluid

The properties are better studied using tensor-valued constitutive equations, which are common in the field of continuum mechanics.

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

Several examples are clay suspensions, drilling mud, toothpaste, mayonnaise, chocolate, and mustard.

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).

These include:[15][16][17][18][19][20] An inexpensive, non-toxic example of a non-Newtonian fluid is a suspension of starch (e.g., cornstarch/cornflour) in water, sometimes called "oobleck", "ooze", or "magic mud" (1 part of water to 1.5–2 parts of corn starch).

[25] Another example of non-Newtonian fluid flow is chilled caramel ice cream topping (so long as it incorporates hydrocolloids such as carrageenan and gellan gum).

The sudden application of force—by stabbing the surface with a finger, for example, or rapidly inverting the container holding it—causes the fluid to behave like a solid rather than a liquid.

[26] Silly Putty is a silicone polymer based suspension that will flow, bounce, or break, depending on strain rate.

Quicksand's non-Newtonian properties can be observed when it experiences a slight shock (for example, when someone walks on it or agitates it with a stick), shifting between its gel and sol phase and seemingly liquefying, causing objects on the surface of the quicksand to sink.

Under certain circumstances, flows of granular materials can be modelled as a continuum, for example using the μ(I) rheology.

Such continuum models tend to be non-Newtonian, since the apparent viscosity of granular flows increases with pressure and decreases with shear rate.

Classification of fluids with shear stress as a function of shear rate.
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.
Demonstration of a non-Newtonian fluid at Universum in Mexico City
Oobleck on a subwoofer. Applying force to oobleck, by sound waves in this case, makes the non-Newtonian fluid thicken. [ 21 ]
Slime flows under low stresses but breaks under higher stresses