Talk:Rheology

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Extensional Flow

"Extensional flow" is used without a definition. It would be nice if someone explicitly explained the manner by which it differs from shear flow, since it was actually the search term that brought me to this page. — Preceding unsigned comment added by 128.112.33.239 (talk) 18:31, 19 April 2013 (UTC)[reply]

Rheology vs Fluid Dynamics?

The relation between rheolohy and fluid dynamics?

Rheology is a subset of Fluid Dynamics. Still 22:43, 1 November 2005 (UTC)[reply]

Deborah Number

There is a note in the section of the Deborah number that it does not apply for the Voigt-model solids. Though in the book 'Contact Mechanics' by K.L. Johnson (and other literature referred to) the Deborah number is used as a dimensionless measure of perceived viscosity of viscoelastic media. Since the Voigt model describes viscoelastic media, I do not understand why this note is included. It remains dimensionless measure of viscosity in both cases. Anyone any thought? Otherwise my suggestion is to remove it here and on the page of the Deborah number. —Preceding unsigned comment added by 129.125.16.57 (talk) 15:41, 2 February 2010 (UTC)[reply]

There are several inaccuracies in this article. One is the limitation on Deborah number, the other one was pointed out below, related to the statement "In practice, rheology is principally concerned with extending the "classical" disciplines of elasticity and (Newtonian) fluid mechanics to materials whose mechanical behaviour cannot be described with the classical theories". I don't understand what they mean by extending to behavior that cannot be described by classical theories - almost everything about continuum rheology is classical. There are few others. I am not sure whether Wikipedia got this article from http://www.chemeurope.com/en/encyclopedia/Rheology.html or they got it from here. In any case there are few other miss-statements that needs to be addressed. --Kijacob (talk) 12:00, 10 September 2011 (UTC)[reply]

I am going to comment out this line: "Note that the Deborah number is relevant for materials that flow on long time scales (like a Maxwell fluid) but not for the reverse kind of materials (Kelvin–Voigt materials) that are viscous on short time scales but solid on the long term". From what I understand, this is not really true. But if anyone disagrees, please let me know. In the ideal cases, for a Maxwell material, the relaxation time is shorter, a Kelvin material will show a larger relaxation time, and a pure elastic solid (without any viscosity) will have a very very large but probably finite relaxation time, depending on the temperature. For a fixed observation time (thus, keeping the denominator a constant), the Deborah numbers only say that the elastic material is more solid than the Kelvin material, which has more solid like behavior than Maxwell material, and a purely viscous fluid is the least solid like. Also this book (^[1] Rheological methods in food process engineering by James Freeman Steffe, page 333, Eq. 5.65 )clearly uses Deborah number for a Kelvin material. --Kijacob (talk) 00:43, 11 September 2011 (UTC)[reply]

References

^ [http://books.google.com/books?id=LrrdONuST9kC&pg=PA333&lpg=PA333&dq=kelvin+solid+deborah+number&source=bl&ots=kYRNnBbea4&sig=WpYzVGdqJNAigfeo4r-Xg7E3nZk&hl=en&ei=cPxrTp-VIdS4twfuqMTcBQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCsQ6AEwAg#v=onepage&q=kelvin%20solid%20deborah%20number&f=false Rheological methods in food process engineering by James Freeman Steffe, page 333, Eq. 5.65

Error?

The article says: <...> rheology is principally concerned with extending the "classical" disciplines of ELASTICITY and Newtonian fluid mechanics <...>

Modified. --Kijacob (talk) 16:43, 11 September 2011 (UTC)[reply]

but in the diagram we see that it is related with PLASTICITY and Newtoniam fuild mechanics. Which is the correct? nopes read it again —Preceding unsigned comment added by 202.164.33.194 (talk) 07:08, 22 September 2007 (UTC) This will take a little more work to address in a coherent way, I will work on it. --Kijacob (talk) 16:43, 11 September 2011 (UTC)[reply]

The article also claims that engineering is not considered part of rheology. This is inaccurate. The current president of the Society of Rheology is a chemical engineer. —Preceding unsigned comment added by 128.112.34.254 (talk) 13:26, 4 April 2008 (UTC)[reply]

Modified. --Kijacob (talk) 16:43, 11 September 2011 (UTC)[reply]

Something is missing/wrong in this sentence: "One of the tasks of rheology is to empirically establish the relationships between deformations and stresses, respectively their derivatives by adequate measurements." —Preceding unsigned comment added by 93.97.51.232 (talk) 15:05, 23 January 2009 (UTC)[reply]

modified --Kijacob (talk) 16:43, 11 September 2011 (UTC)[reply]

Rheological Additives

This site has a great, easy to read explanation of rheology: http://www.specialchem4coatings.com

Copyright problem removed

Prior content in this article duplicated one or more previously published sources. The material was copied from: http://digitallibrary.srmuniv.ac.in/dspace/bitstream/123456789/8878/1/P5018.pdf http://books.google.com.et/books/about/Viscoelastic_Properties_of_Polymers.html?id=9dqQY3Ujsx4C http://oregonite.blogspot.com/2007/10/biopolymer-versus-polymers.html http://www.google.com/patents/US6187837 http://doct-us.usv.ro/article/viewFile/84/42. Copied or closely paraphrased material has been rewritten or removed and must not be restored, unless it is duly released under a compatible license. (For more information, please see "using copyrighted works from others" if you are not the copyright holder of this material, or "donating copyrighted materials" if you are.) For legal reasons, we cannot accept copyrighted text or images borrowed from other web sites or published material; such additions will be deleted. Contributors may use copyrighted publications as a source of information, but not as a source of sentences or phrases. Accordingly, the material may be rewritten, but only if it does not infringe on the copyright of the original or plagiarize from that source. Please see our guideline on non-free text for how to properly implement limited quotations of copyrighted text. Wikipedia takes copyright violations very seriously, and persistent violators will be blocked from editing. While we appreciate contributions, we must require all contributors to understand and comply with these policies. Thank you. ParacusForward (talk) 22:34, 9 February 2014 (UTC)[reply]

Magneto- and Electrorheological fluids

Would someone technically qualified add a section referencing the in-depth articles on magnetorheological and electrorheological fluids? The commercial applications, especially automotive, are making them more and more technically useful in common everyday machines and devices. As such, it would be beneficial to link the subjects for ease of exploration by the readers. Gil gosseyn (talk) 14:44, 30 July 2016 (UTC)[reply]

These topics are certainly interesting and relevant - but they do not fit with this page. The page Non-Newtonian fluid would be better, but it should have it's own page, I think. (Which may even exisit, I did not check.)

Volker Siegel (talk) 15:04, 19 August 2016 (UTC)[reply]

subsection 4.5 concrete rhology

This ending "Their addition highly improves concrete and mortar properties" sounds like wesel words. And it does not realy add anything to the article's topic (rheology that is). Removing (delete, that is) this sentence from the article would highly improve the article's properties. 89.134.199.32 (talk) 22:49, 17 August 2018 (UTC).[reply]

Gases

The first sentence claims it applies to liquids and gases. Are there any gases which display this complex behaviour? Chemical Engineer (talk) 20:27, 15 May 2022 (UTC)[reply]

[1] [http://books.google.com/books?id=LrrdONuST9kC&pg=PA333&lpg=PA333&dq=kelvin+solid+deborah+number&source=bl&ots=kYRNnBbea4&sig=WpYzVGdqJNAigfeo4r-Xg7E3nZk&hl=en&ei=cPxrTp-VIdS4twfuqMTcBQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCsQ6AEwAg#v=onepage&q=kelvin%20solid%20deborah%20number&f=false Rheological methods in food process engineering by James Freeman Steffe, page 333, Eq. 5.65

[1]