Talk:Dilatant

Someone removed Custard as an example. Custard is most definitely dilatant, though it depends on the thickness to which it is mixed - custard that has set or else is very thin and runny isn't noticably dilatant. It has to be "just right". How do I know this - well, partly common experience. But also, there was a memorable demonstration on UK TV once, for a show about science (forget its name, but it was the one with Magnus Pyke). They filled an entire bathtub with custard, They got a few volunteers to roll up their trousers and walk through it. Of course, you could walk (or wade) through the custard. Then they got them to RUN through it. The custard supported their weight and so instead they ran across the top of it. The effect was quite remarkable! The reason was the dilatant property - the force of a running foot striking the surface caused the dilatant liquid to thicken locally and become more viscous, supporting the weight. Finally, consider that custard is mostly corn starch and water, with egg and vanilla flavouring added, and as corn startch is already mentioned, its dilatant properties should not be all that surprising.

Mechanics Reference
I added an explanation to how dilatants work on a molecular scale, and i have a source, but i'm not sure how to add it. I copied some code and pasted to the edit page, putting in the relevant source, and it created a footnote number, but not a reference section at the end of the article, could someone who knows how references work fix this? The source is an encyclopedia: Editor: Nicholas P Cheremisihoff, Source: Encyclopedia of Fluid Mechanics: Rheology and Non-Newtonian Flows, Volume: 7, Publisher: Gulf Publishing Company, Houston, Texas, 1988. Thanks! —Preceding unsigned comment added by Cas315 (talk • contribs) 16:05, 11 November 2008 (UTC)

Silly putty
Silly putty page says silly putty is not strictly dilatent: perhaps a different example should be used


 * The problem with giving "good" examples is that most non-Newtonian fluids don't fall neatly into a single category, nor are the categories mutually exclusive. Dilatant means that a fluid thickens under shear, and Silly Putty most definately does exhibit that property--yank it, it snaps, hit it with a hammer, it shatters.  Silly putty is also visco-elastic, in that in its thickened state, it rebounds after deformation, which is why after it snaps it rebounds, and when thrown at the floor, it bounces.  I have been meaning to re-do the chart at the non-Newtonian fluid article (see Talk:Non-Newtonian_fluid) to make this more clear, as other people have expressed confusion over different example substances also appearing in other categories.  scot 14:33, 24 Jun 2005 (UTC)


 * It seems to me that if silly putty is not a dilatant, we should not give it as an example as one even if it demostrates some of the properties of one. However if you do wish to include it, I think you need to at least mention it is not a dilatant even if it shows similar properties Nil Einne 15:14, 11 November 2006 (UTC)

Possible vandalism alert
Slashdot recently linked to an article that prominently linked to this page on Wikipedia so keep your eye out for vandals. --⁪froth T C  07:42, 4 January 2007 (UTC)

Rheology A non-Newtonian fluid is a fluid whose viscosity is variable based on applied stress. The most commonly known non-Newtonian fluid is cornstarch dissolved in water. Contrast with Newtonian fluids like water, whose behavior can be described exclusively by temperature and pressure, not the forces acting on it from second to second. Non-Newtonian fluids are fascinating substances that can be used to help us understand physics in more detail, in an exciting, hands-on way. If you punch a bucket full of a shear thickening non-Newtonian fluid, the stress introduced by the incoming force causes the atoms in the fluid to rearrange such that it behaves like a solid. Your hand will not go through. If you shove your hand into the fluid slowly, however, it will penetrate successfully. If you pull your hand out abruptly, it will again behave like a solid, and you can literally pull a bucket of the fluid out of its container in this way. A shear thinning non-Newtonian fluid behaves in the opposite way. In this type, the fluid becomes thinner, rather than thicker, when stress is applied. Also called pseudoplastic, examples of this type of non-Newtonian fluid include ketchup, toothpaste, and paint. The effect doesn't usually last for long in either type, continuing only as long as the stress is applied. Non-Newtonian fluids help us understand the wide variety of fluids that exist in the physical world. Plastic solids, power-law fluids, viscoelastic fluids, and time-dependent viscosity fluids are others that exhibit complex and counterintuitive relationships between shear stress and viscosity/elasticity. However, non-Newtonian fluid is probably the most exciting to play with. A search for non-Newtonian fluid on YouTube brings up some interesting results. On several game shows, hosts or contestants run across big vats of shear thickening non-Newtonian fluid, able to traverse them unless they stop - in which case they sink immediately. When combined with a oscillating plate, non-Newtonian fluids demonstrate other unusual properties, like protruding "fingers" and holes that persist after creating them. An oscillating plate applies stress on a periodic basis, rapidly changing the viscosity of the fluid and putting it in an odd middle ground between a liquid and a solid. —Preceding unsigned comment added by 129.111.80.174 (talk) 21:28, 16 September 2010 (UTC)

The Table of viscosity values of various materials is incorrect. The decimal places for a number of the entries are misplacedGgjik (talk) 23:51, 19 October 2011 (UTC)ggjik.

Edits to Small-Arms Application
Dear user 71.22.156.40: Your edits to the Dilatant page appear improper. First, attempting to “out” the editor (“reverted possible self-promotion or marketing...by Jason Jackson of Charybdis Research”) may be viewed as a form of harassment: “Posting another editor's personal information is harassment. . . Posting such information about another editor is an unjustifiable and uninvited invasion of privacy and may place that editor at risk of harm outside of their activities on Wikipedia.” (http://en.wikipedia.org/wiki/Wikipedia:OUTING#Posting_of_personal_information).

Second, the material you deleted was under the “Applications” heading on the Dilatant Wikipedia page. I believe that the use of shear thickening fluid (STF) for small-arms is a new, useful, and exciting application, much like the use of STF for liquid body armor. Moreover, the contribution is backed-up by a U.S. Patent that describes and enables the use of STF with small-arms ammunition. If you disagree with the particular application or the science, please explain your position (with citations) – otherwise, I believe that the application of STF to small-arms ammunition warrants inclusion as an Application on this page.

In an effort to reach an amicable resolution, I’m happy to consider your revisions (or those of another editor) – less than an entire deletion – to the paragraph. Please let me know how you intend to proceed. Best regards - Makarov — Preceding unsigned comment added by Master Makarov (talk • contribs) 22:56, 9 August 2012 (UTC)

You outed yourself when you included the following information on the “Gas-operated reloading” page…… Dual-mode Impingement-Piston In May 2012, Jason Jackson of Charybdis Research patented a dual-mode, direct-impingement and gas-piston system. The system enables a user to operate a rifle by either direct-impingement or gas-piston operation on a shot-by-shot basis. The patent describes an operating rod with an integral gas tube. Depending on how the operating rod is positioned in a gas block, gas can either be directed into the gas tube for direct-impingement operation, or against the operating rod for gas-piston operation. A user might select the direct-impingement mode for precision shooting or for shorter automatic bursts, while a user might select the gas-piston mode for suppressed fire or for high-volume fire (each of which tends to foul the receiver at a faster rate in direct-impingement operation). As shown in the patent, the system is well suited for AR-15-type rifles and can be used, for example, with an AR-type bolt carrier group. As stated on the “Gas-operated reloading talk page”…There are hundreds of thousands of firearm patents, most have never gone into production, will never go into production, or were only produced as proto-types. We simply don’t have room to discuss every single one. We should only discuss those systems that have gone into mass production. Therefore, I have removed said information. Also, the information provided could be considered self-promotion or marketing which is strictly prohibited by Wikipedia.

If you wish to include “shear thickening fluid (STF) for small-arms” in this article it’s fine with me…However, you can make no mention of yourself, your company or your patents. — Preceding unsigned comment added by 71.22.156.40 (talk) 00:42, 12 August 2012 (UTC)

Sources modified on Dilatant
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External links modified (January 2018)
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Incorrect top image?
It seems the top image in this article is incorrect. Shear-thickening fluids have a viscosity that increases with shear stress, and shear-thinning fluids have a viscosity that decreases with shear stress. See a correct image in this article: https://en.wikipedia.org/wiki/Non-Newtonian_fluid 2A02:AA10:E27E:E400:70A7:E076:F4CB:8A41 (talk) 15:27, 6 January 2019 (UTC)