Talk:Non-Newtonian fluid

Blood

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

An Answer: According to Fung (Fung, Y.C., Biomechanics : circulation. 2nd ed. 1997, New York: Springer. xvii, bottom of page 53) "blood is a non-newtonian incompressible viscoplastic fluid". However, blood is composed of cells suspended in plasma. The plasma IS a newtonian fluid, while whole blood is not. —Preceding unsigned comment added by 137.53.254.66 (talk) 02:07, June 11, 2007

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 second that: Yes, someone with knowledge of this, please fix the table, and the graph. Maybe a new graph for the time dependent viscosity properties, of thixotrophy and rheopexy)? --Rajah (talk) 01:11, 29 June 2008 (UTC)

I agree the table is confusing and needs to be changed. What about the compounds that are subsets of the grouping? Some have properties of more than one group. —Preceding unsigned comment added by 209.152.67.222 (talk) 17:02, September 15, 2006

Proposed new table

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)

I saw the recent reports of research on shear thickening fluid based composites for body armor. Damnit, I should have patented that when I first thought of it, over 15 years ago. Never did get around to putting together a sample of Silly Putty and Kevlar composite and shooting it, however... scot 14:55, 25 Mar 2005 (UTC)

I agree the table is confusing and needs to be changed. What about the compounds that are subsets of the groupings? They have properties of more than one group. akozak —Preceding unsigned comment added by 209.152.67.222 (talk) 17:06, September 15, 2006

Terminology

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

Boger Fluids

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

That would be a visco-elastic fluid. From this article http://www.theage.com.au/news/national/300000-boger-fluid-prize-not-on-the-nose/2005/10/04/1128191716871.html it soulds like the Boger fluid is a pretty rare thing--most of the traditional visco-elastic fluids, like shear thickening Silly Putty, also exhibit non-Newtonian viscosity changes. In fact, I think most of the visco-elastic substances would be shear thickening, as shear thinning would seem to be incompatable with elasticity.... scot 14:13, 7 October 2005 (UTC)

I'm not sure if this resolves anything, but Boger fluids exhibit constant viscosity; however their shear properties don't satisfy the equation required for classification as Newtonian, so they're a unique class of non-Newtonian fluid. Jelliott4 (talk) 13:25, 16 March 2011 (UTC)

External links of interest

http://www.research-equipment.com/viscosity chart.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 Bad Edit

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

Double Listing

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

Many fluids exhibit more than one non-Newtonian behavior; for example, Silly Putty is both shear thickening and visco-elastic. It's entirely possible that blood exhibits a number of non-Newtonian behaviors, and that pseudo-plastic just happens to be the dominant trait. See the above discussion for my earlier suggestions on reorganizing the chart to make these overlaps less confusing. scot 23:50, 4 February 2006 (UTC)

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)

Ah, taking out the "non" in front of "newtonian" certainly makes a difference. It is the case that some fliuds exhibit Newtownian behavior under some circumstances and not under other circumstances. My guess is that bood does exhibit non-Newtownian behavior at times, as it is a suspension of particles (cells) in a fluid (plasma) and such suspensions often behave oddly--corn starch in water, for example, which exhibits pretty radical shear thickening, or iron particles in oil, which thickens in the presence of a magnetic field (making it a magnetorheological fluid). My guess is that that the issue is at what point you split a fulid into "Newtownian" or "Non-Newtownian" categories. Probably all fluids behave in a non-Newtownian manner under the right circumstances (particularly at very small scales), and it's all a matter of picking the threshold. scot 16:47, 9 February 2006 (UTC)

Maxwell Material

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

Merger proposal

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)

The article on complex fluids seems mostly interested in multiphasic flow. Which is completely different from being non-newtonian. So I think the merger should not happen. CyrilleDunant (talk) 08:51, 17 November 2007 (UTC)

CyrilleDunant is correct - the merger should not happen. Those that suggested it no nothing about basic Physics. —Preceding unsigned comment added by 86.143.220.162 (talk) 23:15, 21 November 2007 (UTC)

eggs

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)

Possible graphs

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

• 
  Dilatant and pseudoplastic behavior
• 
  Thixotropic and rheopectic behavior
• 
  Bingham plastic behavior
• 
  Viscoelastic fluid behavior

Requested move

The result of the proposal was keep the N capitalized. [sd] 13:23, 24 June 2009 (UTC)

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

Newtonian is an adjective, thus should be uncapitalized.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:37, 29 March 2009 (UTC)

While it is an adjective, it is also derived for a person's name. In my experience such things are capitalized more often then not (even as adjectives) and so the capitalization makes sense. Dragons flight (talk) 07:08, 29 March 2009 (UTC)

I agree with Dragons flight. There are plenty of examples of adjectives derived from personal names that are usually capitalised. Off the top of my head I can think of Dickensian, Darwinian, Euclidean, Aristotelian. Cadwaladr (talk) 15:12, 29 March 2009 (UTC)

Add Orwellian. There is one well-known exception (abelian) but this is not it. Septentrionalis PMAnderson 22:08, 30 March 2009 (UTC)

I've never seen Newtonian not be capitalized, in papers or textbooks - maybe I hang out in a different section of the literature than Headbomb. It seems that there is some consensus to not move? Awickert (talk) 09:02, 3 April 2009 (UTC)

(Reset) The scope of Elsevier's Journal of Non-Newtonian Fluid Mechanics includes problems involving heat and mass transfers and mixing in flowing non-Newtonian liquids and instabilities, unsteady and turbulent or chaotic flow characteristics in non-Newtonian fluids. Thus, the publisher favors capitalizing N. [sd] 03:50, 24 June 2009 (UTC)

Although I agree that it should be capitalized, it could be argued that it was simply capitalized as part of the title there. In any case, I think the discussion can be closed in favor of keeping the "N". —Preceding unsigned comment added by Awickert (talk • contribs) 06:16, June 24, 2009

To clarify, yes, Newtonian is capitalized in the journal's title, but it is also capitalized in sentences like the ones above (in which non is left uncapitalized while Newtonian is capitalized). [sd] 13:19, 24 June 2009 (UTC)

The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Urine

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)

Urine is (as far as I know, usually, at normal temperature and pressure conditions, baring certain medical conditions) adequately simulated using a Newtonian approximation. As for the classification scheme, no. It might depend on temperature, scale considered, speed, etc. Fluids themselves are not Newtonian or not: it is only a way of saying that for the state/conditions considered a linear approximation of the behaviour is satisfactory or not.CyrilleDunant (talk) 12:17, 15 August 2009 (UTC)

Appreciated. __meco (talk) 12:25, 15 August 2009 (UTC)

What is the photo illustrating?

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)

Nobody has put in an explanation since you asked, and it's useless without one.71.203.125.108 (talk) 15:38, 16 May 2010 (UTC)

Here is a link to a video that shows what I can only assume the photo is trying to depict. http://www.youtube.com/watch?v=F2i-IPiuCwk&NR=1 98.173.153.226 (talk) 20:05, 10 September 2010 (UTC)

The opening paragraph is too confusing

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)

Custard listed as a Newtonian Fluid

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)

Isnt Viscoelastic fluids time dependent?

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)

Questionable fact/date

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)

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)

Table heading

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)

Cornstarch

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)

Non-definition of viscosity

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)

Okay—I get it now, the emphasis is on constant. I had missed the sentence about linearity. — MaxEnt 11:28, 10 September 2017 (UTC)

Oobleck: O or o?

The article currently has it both ways. 2.24.119.66 (talk) 00:49, 6 May 2018 (UTC)

I'm not 100% sure, but it doesn't seem to be a proper name, so I have standardised this with lower case O. Bazonka (talk) 17:42, 17 March 2019 (UTC)

Newtonian Fluid

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)