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Blood shows up in two seemingly mutually exclusive examples. Anyone know the correct answer? —Preceding unsigned comment added by Penguin020 (talk • contribs) 00:08, July 27, 2004
Classification of generalized Newtonian fluids
I think that the table in the article could be improved. For example, it shows (or suggests) that power-law fluids, Bingham plastics, and generalized Newtonian fluids are distinct categories of non-Newtonian fluids. Rheology and fluid mechanics textbooks classify power-law fluids and Bingham plastics as subsets of generalized Newtonian fluids. (A clarification concerning this point would also address the confusion over the classification of blood, noted in the preceding section.) YinDW 00:15, 12 Jan 2005 (UTC)
I think YinDW is right, I think the table is just confusing. Many of the attributes of non-Newtonian fluids are orthogonal; it is, for example, possible to have a dilatant material that exhibits viscoelasticity (Silly Putty), or a plastic solid that is Newtonian past the yield point (grease). How's this:
Type of fluid | Also known as | Behaviour |
Dilatant | shear thickening | viscosity increases as shear rate increases |
Pseudoplastic | shear thinning | viscosity decreases as shear rate increases |
Thixotropic | viscocity decreases with duration of shearing force | |
Rheopectic | viscocity increases with duration of shearing force | |
Viscoelastic | fluid will rebound when shear force is removed | |
Plastic solid | substance that will not flow with shearing force below a threshold called the yeild point |
And it should be pointed out explicitly that many non-Newtonian fluids exhibit more than one characteristic; perhaps a chart that lists substances in the left column, and the non-Newtonian characteristics to the right:
Substance | Non-Newtonian properties |
Silly Putty | Viscoelastic, shear thickening |
Lubricating grease | Plastic solid |
Ketchup | Thixotropic, pseudoplastic |
Gypsum paste | Rheopectic |
And as should be apparent from the horrid formatting of my tables, I'll probalby need some help cleaning them up if I do this... scot 20:30, 4 Mar 2005 (UTC)
There seems to be a misunderstanding about some of the terminology. For example, the IUPAC definition of rheopexy does NOT agree with the above (see IUPAC website). In J. Rheology and Rheological acta people distuingish between positive thix, negative thix and rheopexy. See f.e. J. Rheol. 48(6), 2004, 1279-1293 and J. Rheol. 49(4), 2005, 839-849. Many rheological textbooks are not so detailed and just write that negative thix equals rheopexy but are, to my humle opinion, not correct. I fully agree with the first remark of this section in that it is possible to have more than one fluid types combined in one fluid (pseudoplastic and negative thix). I suggest to delete the table because it suggests otherwise.
regards, anthonie —Preceding unsigned comment added by 144.95.32.4 (talk) 15:56, February 8, 2006
Where do constant-viscosity elastic (Boger) Fluids fit into this classification scheme? —Preceding unsigned comment added by 61.88.61.66 (talk) 02:44, October 7, 2005
http://www.research-equipment.com/viscosity%20chart.html
http://www.edasolutions.com/Groups/sizepump.htm
http://www.physics.mun.ca/~phabdas/physics/rheo.html
Isn't a Dilaltant fluid under the same category as rheopectic? Due to its similar flow properties. —Preceding unsigned comment added by Fluzwup (talk • contribs) 21:53, March 4, 2005
Sorry I added YouTube video link and did not noticed it exist in external links. Can you please revert last change? —Preceding unsigned comment added by 69.37.120.14 (talk) 23:51, November 11, 2006
Blood is listed as both a pseudo-plastic and generalized newtonian fluid. Is this accurate? —Preceding unsigned comment added by Tuckerekcut (talk • contribs) 23:37, February 4, 2006
I understand that a given material may be capable of exhibiting more than one non-newtonian characteristic, but in this case, blood is listed both as a pseudo-plastic (a non-newtonian fluid) and a generalized newtonian fluid (a newtonian fluid). How can blood be both newtonian and non-newtonian? I admittedly know very little about fluid dynamics, and it may be possible that these categories are not mutually exclusive, but from what I understand that is only likely to be true if a single fluid changed from newtonian to non-newtonian behavior through some exterior stimulus (pressure, temperature &c.). Tuckerekcut 16:29, 9 February 2006 (UTC)[reply]
As examples of a Maxwell material, the table lists metals and composites. This does not seem correct. As explained on the actual page for Maxwell Material, a Maxwell Material is a liquid, since it does not rebound on deformation. Metals are first and foremost elastic, unless deformed past their yield points. —Preceding unsigned comment added by Yapete (talk • contribs) 19:56, November 1, 2006
I propose Complex fluids be merged with this page. Complex fluid is already redirected here. I'm not an expert on fluid mechanics, so I don't know if this makes sense. I'll help merge if it does. -FrankTobia (talk) 03:42, 17 November 2007 (UTC)[reply]
I know that eggs don't behave like a newtonian fluid... for an easy example, make a scrambled egg. As you stir the egg faster, it slops around less. Don't know how this would get classified or anything though. —Preceding unsigned comment added by 137.112.141.205 (talk) 19:20, 5 December 2007 (UTC)[reply]
I made some graphs for possible inclusion here that attempt to illustrate the idealized properties of the non-Newtonian fluid behaviors mentioned above as compared to Newtonian behavior, as well as I understand said behaviors. Feel free to insert them if they seem correct, or I/others can make adjustments. —Preceding unsigned comment added by DirectEON (talk • contribs) 09:00, March 28, 2008
The result of the proposal was keep the N capitalized. [sd] 13:23, 24 June 2009 (UTC)[reply]
Newtonian is an adjective, thus should be uncapitalized.Headbomb {ταλκκοντριβς – WP Physics} 06:37, 29 March 2009 (UTC)[reply]
Is urine a Non-Newtonian fluid? Also, would it be appropriate to request a scheme whereby all fluids are classified as either Newtonian or Non-Newtonian? __meco (talk) 10:01, 15 August 2009 (UTC)[reply]
What does the photo of the corn starch on the speaker demonstrate? It doesn’t seem to be referenced anywhere in the article (unless I missed it), and I can’t imagine what it is meant to be showing - does it go solid when you turn the speaker on, or liquify, or levitate, or what?79.67.148.152 (talk) 11:02, 25 November 2009 (UTC)[reply]
The opening paragraph does not really describe a Non-Newtonian fluid. Ideally an opening paragraph should explain what it is, not that it is simply 'not something'. The Newtonian Fluid description could be modified to fit the opening paragraph. I'd do it myself, but unlike some wikipedia bureaucrats who throw their weight around trying to simplify or standardize fields they know nothing about, I'd prefer if someone else with expertise handle this because articles of this nature should be handled by experts rather than just someone with a plan to make this comply to some esoteric standard. Klichka (talk) 21:36, 6 April 2011 (UTC)[reply]
Custard is listed in the table as a Newtonian fluid. This is contradicted by comment under section on "Bingham plastic" which says that "...Newtonian fluids have flat featureless surfaces when still", which is not true of custard. It is also contradicted by comment on custard page stating that custard is thixotropic. See http://en.wikipedia.org/wiki/Custard.
Does "custard" have divergent enough meanings that both categorizations could be true in different situations? Tom10001 (talk) —Preceding undated comment added 19:31, 28 January 2013 (UTC)[reply]
In the first table of non-newtonian page, viscoelasticity has been set separate from time dependent non-newtonian fluids. but "Viscoelastic materials have elements of both of these properties and, as such, exhibit time-dependent strain." from Viscoelasticity. — Preceding unsigned comment added by Aditya8795 (talk • contribs) 12:51, 1 September 2014 (UTC)[reply]
The Cary Sneider quote I object to is also from 2013 and certainly not the first use of goop in a classroom. Reverted User:Fuborc edit.--Lucas559 (talk) 21:04, 17 June 2015 (UTC)[reply]
May I ask if you have any earlier documented uses of cornstarch and water slurry in a formal educational setting? It would certainly be good to have the original use documented here. Dr Sneider claims his use in 1969 was the first such use, and I have not found any earlier accounts. Fuþorc (talk) 16:07, 13 November 2015 (UTC)[reply]
The table "Comparison of non-Newtonian, Newtonian, and viscoelastic properties" would be more useful with headings. Columns 1, 3 and 4 could be "Type", "Properties" & "Examples" but I'm not sure about column 2. Tigerboy1966 07:44, 1 January 2017 (UTC)[reply]
The article states that cornstarch 'dissolved in water' displays shear thickening. This is wrong since the phenomenon referred to concerns cornstarch dispersed at high concentration in cold water. This doesn't dissolve the starch to any significant extent and the thickening observed is due to the cubic starch particles bunching up and not flowing past each other when any more than a small force is applied. It's analogous to the picture with wet sand. A true cornstarch solution (made by dissolving/cooking in very hot water) is actually more like a gel, and non-Newtonian in the more common pseudoplastic sense. — Preceding unsigned comment added by 81.102.219.142 (talk) 18:06, 15 August 2017 (UTC)[reply]
In a non-Newtonian fluid, the relation between the shear stress and the shear rate is different. The fluid can even exhibit time-dependent viscosity. Therefore, a constant coefficient of viscosity cannot be defined.
I just dividing a sentence to eliminate an awkwardness. This made the original text more problematic in meaning: the original text seemed to want to imply that the first sentence (and not what I have now placed in the second sentence) on its own is sufficient to justify the third sentence, but the line of implication is locally opaque to me (and I didn't first read and comprehend the entire article). — MaxEnt 11:25, 10 September 2017 (UTC)[reply]
The article currently has it both ways. 2.24.119.66 (talk) 00:49, 6 May 2018 (UTC)[reply]
This article implies the existence of Newtonian Fluids. There are none. That is, over the entire range of stress/shear rate, no fluid is Newtonian. The article on Newtonian Fluids says:"While no real fluid fits the definition perfectly, many common liquids and gases, such as water and air, can be assumed to be Newtonian for practical calculations under ordinary conditions." But I know of no fluid that does not have a linear relationship between shear rate and stress IF observed over a sufficiently small range. (Of course, a limiting (infinitesimal) value is required for the existence of the quantity (assuming a continuum).) It would be good to mention that a Newtonian Fluid is a simple ideal case which many fluids approximate in common situations, but no fluids* follow Newton's Law of Constant Viscosity perfectly over the entire range of shear rate. Non-Newtonian Fluids exhibit a non-linear (non-constant) shear/stress curve under common 'normal' (i.e. non extreme) situations. *I don't know if superfluids (e.g. He-3 or He-4 at cryogenic temperatures), have zero viscosity over the entire shear rate range, but I'd guess not.(of course, that assumes we can create indefinitely large or small shears, and we clearly can't.)207.155.85.22 (talk) 23:48, 20 February 2022 (UTC)[reply]