Thixotropic Fluid is a time-dependent fluid in which velocity is based upon shear stress and time duration of application. The non-Newtonian fluid has a value of B = ty and n = 1 because it has a starting value of B that is greater than 0, thus its viscosity gradient is enhanced from that point.Īn example of Bingham plastic is sewage slug, drilling mud Thixotropic Fluid: The non-Newtonian fluid has a value of B = 0 and the value of n is less than 1 in the general equation, thus the graph is gradually decreased.Įxample of Pseudoplastic fluid: Blood, rubber, paints, etc. The non-Newtonian fluid has a value of B = 0 and the value of n is more than 1 in the general equation, thus the graph is gradually increased.Įxample of Dilatant fluid: Butter and Quicksand etc. It is therefore extremely difficult to make and sustain Helium as a superfluid but it does have some incredible properties, with a zero viscosity it flows with no friction and can escape containers literally by flowing up the sides of the container against gravity and produce fountains that in theory would last forever (although only as long as the supefluidity state is maintained).Non-Newtonian Fluid Types of Non-Newtonian fluid: Dilatant Fluid: Helium 3 and 4 (isotopes) have been made into superfluids in the past, they have to be cooled to below their liquefaction point (which itself is extremely low at about 4 Kelvins) and it can only be liquefied using the Hampson-Linde cycle. This effect was discovered in 1937 by Pyotr Kapitsa, John F Allen and Don Misener. ![]() There are certain occasions when a liquid can in fact have zero viscosity or zero thickness, which is a state of matter known as superfluidity. Some scientists have suggested that ‘shear-thickening’ fluids would be perfect for filling potholes, the actual filling itself would be easy because of the liquid properties and it will then solidify when the wheels of the car run over it. The fluids are perfect for bulletproof vests because of how easily they could be incorporated into a comfortable piece of clothing yet still reliably block a bullet on impact, even removing most of the force then impact of the bullet when it hits. Research is going into using Shear thickening fluids for many different applications, including Bulletproof vests and the filling of potholes. Of these types of Non-Newtonian fluids ‘Shear Thickening’ fluids have the most real world uses, excluding the many extremely cool experiments you can see on YouTube of which my favourites are: Graph showing various Non-Newtonian fluids’ properties Liquids that seemingly become solidified when under pressure are known as ‘Shear-Thickening’ or ‘Dilatant’ Non-Newtonian Fluids and include as examples sand in water (a sort of quicksand), Silly Putty and finally a combination of corn starch in water. Non-Newtonian fluids that become less viscous with an increase in pressure are know as ‘Shear-Thinning’ or pseudo-plastic examples of this are Ketchup, Nail varnish, syrups and blood. Those Non-Newtonian fluids that lose viscosity as the length of time they are under pressure increase are known as Thixotropic and have a huge number of examples including Yoghurt, many paints and Synovial fluid (found in joints in animals) A third type are Non-Newtonian fluids that get less viscous as the length of time pressure is applied increases. However this is just one way fluids can disobey Newton’s laws for fluids, there are also Non-Newtonian fluids that get less and less viscous as a greater pressure is applied. This happens because the particles in a Non-Newtonian fluid are packed tighter and closer than in a normal liquid, when the fluid is poured or mixed slowly the particles can slip past each other so it gives the appearance of a liquid, but if there is a sudden application of pressure the particles don’t slip past each other but instead pack tightly like a solid. It appears to change state while under stress. What this means is that when there is an applied pressure the substance, which is a liquid, becomes solid, immediately after the impact it starts to liquify again (as seen in quicksand). The viscosity of a liquid depends on a combination of the size and shape of the particles in it and therefore the friction between them when the fluid flows, Non-Newtonian Fluids have a viscosity that depends on its’ conditions. Viscosity is technically speaking how resistant a liquid is to gradual deformation by shear stress, basically speaking (my preferred explanation) viscosity is how thick a liquid is, with the unit Pascal seconds (or in SI units (kg/SxM). Non-Newtonian Fluids are liquids that, unlike Newtonian fluids (for example water), have a variable viscosity when under stress. ![]() ![]() Some independent research from one of our RGS Physics pupils:
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