Viskoznost

Simulacija tečnosti sa različitim viskoznostima. Tečnost sa desne strane ima veću viskoznost od tečnosti sa leve strane

Viskoznost tečnosti je mera njenog otpora prema deformaciji. To se može predstaviti osobinom „debljine“: na primer, sirup ima veću viskoznost od vode.

Praćenje proticanja tečnosti kroz cevi pokazuje da se svi delovi tečnosti ne kreću istom brzinom. Najveću brzinu imaju delovi tečnosti duž ose cevi, a najmanju delovi uz zidove cevi. Raspored brzina na preseku cevi, normalnom na pravac proticanja tečnosti. Tečnost se kroz cev ne kreće kao celina, već u slojevima koji klize jedan po drugome različitim brzinama. Pri proticanju tečnosti kao da dolazi do njenog „raslojavanja“. Slično se dešava i pri kretanju, na primer ravne daske, tankera ili sprava po mirnom jezeru. Kada se telo pokrene, počinje i voda da se kreće, ali ne kao celina, već po delovima (slojevima) koji imaju različite brzine. Povećanjem rastojanja od plovnog objekta brzina slojeva tečnosti se smanjuje. U tečnostima se javljaju i sile koje se suprotstavljaju kretanju tela kroz tečnosti. Nabrojane činjenice i pojave objašnjavaju se kao posledica postojanja sile unutrašnjeg trenja u tečnostima, viskoznost. Sila viskoznosti usporava proticanje tečnosti i kretanje tela kroz tečnost.

Etimologija

Reč „viskoznost” je izvedena iz latinskog "viscum", što znači imela, u smislu viskoznog lepka napravljenog od bobica imele.

Njutnov zakon za viskoznost

Viskoznost - unutrašnji otpor tečnosti se može definisati preko sile viskoznosti ukoliko je proticanje te tečnosti laminarno. To znači da slojevi tečnosti „klize“ jedan po drugome, ali tako da tečnost iz jednog sloja ne prelazi u drugi. Sila viskoznog kretanja zavisi, pre svega, od vrste tečnosti. Na primer, dok voda kod koje je ta sila relativno slaba, vrlo brzo istekne iz neke posude, ista količina ulja isticaće iz iste posude veoma sporo.

Stoksov zakon viskoznosti

Sila viskoznosti tečnosti utiče na kretanje tela koja se u njoj nalaze (podmornica, ronilac). Naime, tečnost pruža otpor takvom kretanju, a taj otpor potiče od viskoznosti. Tanak sloj tečnosti „prilepljen“ za tela kreće se zajedno sa telom i istom brzinom kao telo. Usled toga se pokreću i ostali slojevi tečnosti.

Literatura

• Hatschek, Emil (1928). The Viscosity of Liquids. New York: Van Nostrand.
• Massey, B. S.; A. J. Ward-Smith (2011). Mechanics of Fluids (Ninth izd.). London; New York: Spon Press. ISBN 9780415602594. OCLC 690084654. 
• Abdulagatov, Ilmutdin M.; Zeinalova, Adelya B.; Azizov, Nazim D. (2006). „Experimental viscosity B-coefficients of aqueous LiCl solutions”. Journal of Molecular Liquids. 126 (1–3): 75—88. ISSN 0167-7322. doi:10.1016/j.molliq.2005.10.006. 
• Assael, M. J.; et al. (2018). „Reference Values and Reference Correlations for the Thermal Conductivity and Viscosity of Fluids”. Journal of Physical and Chemical Reference Data. 47 (2): 021501. Bibcode:2018JPCRD..47b1501A. ISSN 0047-2689. PMC 6463310 . PMID 30996494. doi:10.1063/1.5036625. 
• Balescu, Radu (1975). Equilibrium and Non-Equilibrium Statistical Mechanics. John Wiley & Sons. ISBN 978-0-471-04600-4. 
• Bellac, Michael; Mortessagne, Fabrice; Batrouni, G. George (2004). Equilibrium and Non-Equilibrium Statistical Thermodynamics. Cambridge University Press. ISBN 978-0-521-82143-8. 

• Bird, R. Byron; Stewart, Warren E.; Lightfoot, Edwin N. (2007). Transport Phenomena (2nd izd.). John Wiley & Sons, Inc. ISBN 978-0-470-11539-8. 

• Bird, R. Bryon; Armstrong, Robert C.; Hassager, Ole (1987), Dynamics of Polymeric Liquids, Volume 1: Fluid Mechanics (2nd izd.), John Wiley & Sons 

• Cercignani, Carlo (1975). Theory and Application of the Boltzmann Equation. Elsevier. ISBN 978-0-444-19450-3. 

• Chapman, Sydney; Cowling, T.G. (1970). The Mathematical Theory of Non-Uniform Gases (3rd izd.). Cambridge University Press. 

• Citerne, Guillaume P.; Carreau, Pierre J.; Moan, Michel (2001). „Rheological properties of peanut butter”. Rheologica Acta. 40 (1): 86—96. doi:10.1007/s003970000120. 

• Cramer, M.S. (2012). „Numerical estimates for the bulk viscosity of ideal gases”. Physics of Fluids. 24 (6): 066102—066102—23. Bibcode:2012PhFl...24f6102C. doi:10.1063/1.4729611. hdl:10919/47646 . 

• Doremus, R.H. (2002). „Viscosity of silica”. J. Appl. Phys. 92 (12): 7619—7629. Bibcode:2002JAP....92.7619D. doi:10.1063/1.1515132. 
• Dyre, J.C.; Olsen, N. B.; Christensen, T. (1996). „Local elastic expansion model for viscous-flow activation energies of glass-forming molecular liquids”. Physical Review B. 53 (5): 2171. doi:10.1103/PhysRevB.53.2171 . 
• Edgeworth, R.; Dalton, B.J.; Parnell, T. (1984). „The pitch drop experiment”. European Journal of Physics. 5 (4): 198—200. Bibcode:1984EJPh....5..198E. doi:10.1088/0143-0807/5/4/003. Pristupljeno 2009-03-31. 
• Egelstaff, P. A. (1992). An Introduction to the Liquid State (2nd izd.). Oxford University Press. ISBN 978-0-19-851012-3. 

• Evans, Denis J.; Morriss, Gary P. (15. 10. 1988). „Transient-time-correlation functions and the rheology of fluids”. Physical Review A. 38 (8): 4142—4148. Bibcode:1988PhRvA..38.4142E. PMID 9900865. doi:10.1103/PhysRevA.38.4142. CS1 održavanje: Format datuma (veza)
• Fellows, P. J. (2009). Food Processing Technology: Principles and Practice (3rd izd.). Woodhead. ISBN 978-1845692162. 

• Fluegel, Alexander (2007). „Viscosity calculation of glasses”. Glassproperties.com. Pristupljeno 2010-09-14. 
• Gibbs, Philip (januar 1997). „Is glass liquid or solid?”. math.ucr.edu. Pristupljeno 19. 9. 2019. CS1 održavanje: Format datuma (veza)
• Gyllenbok, Jan (2018). „Encyclopaedia of Historical Metrology, Weights, and Measures”. Encyclopaedia of Historical Metrology, Weights, and Measures. Volume 1. Birkhäuser. ISBN 9783319575988. 
• Hildebrand, Joel Henry (1977). Viscosity and Diffusivity: A Predictive Treatment. John Wiley & Sons. ISBN 978-0-471-03072-0. 

• Holman, Jack Philip (2002). Heat Transfer. McGraw-Hill. ISBN 978-0-07-112230-6. 
• Incropera, Frank P.; et al. (2007). Fundamentals of Heat and Mass Transfer. Wiley. ISBN 978-0-471-45728-2. 
• Irving, J.H.; Kirkwood, John G. (1949). „The Statistical Mechanical Theory of Transport Processes. IV. The Equations of Hydrodynamics”. J. Chem. Phys. 18 (6): 817—829. doi:10.1063/1.1747782. 

• Kestin, J.; Ro, S. T.; Wakeham, W. A. (1972). „Viscosity of the Noble Gases in the Temperature Range 25–700°C”. The Journal of Chemical Physics. 56 (8): 4119—4124. Bibcode:1972JChPh..56.4119K. ISSN 0021-9606. doi:10.1063/1.1677824. 
• Kestin, J.; Khalifa, H.E.; Wakeham, W.A. (1977). „The viscosity of five gaseous hydrocarbons”. The Journal of Chemical Physics. 66 (3): 1132. Bibcode:1977JChPh..66.1132K. doi:10.1063/1.434048. 
• Koocheki, Arash; et al. (2009). „The rheological properties of ketchup as a function of different hydrocolloids and temperature”. International Journal of Food Science & Technology. 44 (3): 596—602. doi:10.1111/j.1365-2621.2008.01868.x. 
• Krausser, J.; Samwer, K.; Zaccone, A. (2015). „Interatomic repulsion softness directly controls the fragility of supercooled metallic melts”. Proceedings of the National Academy of Sciences of the USA. 112 (45): 13762. doi:10.1073/pnas.1503741112 . 
• Kumagai, Naoichi; Sasajima, Sadao; Ito, Hidebumi (15. 2. 1978). „Long-term Creep of Rocks: Results with Large Specimens Obtained in about 20 Years and Those with Small Specimens in about 3 Years”. Journal of the Society of Materials Science (Japan). 27 (293): 157—161. Šablon:NAID. Pristupljeno 2008-06-16. CS1 održavanje: Format datuma (veza)

• Landau, L. D.; Lifshitz, E.M. (1987). Fluid Mechanics (2nd izd.). Elsevier. ISBN 978-0-08-057073-0. 
• Lesieur, Marcel (2012). Turbulence in Fluids: Stochastic and Numerical Modelling. Springer. ISBN 978-94-009-0533-7. 
• Mewis, Jan; Wagner, Norman J. (2012). Colloidal Suspension Rheology. Cambridge University Press. ISBN 978-0-521-51599-3. 
• McNaught, A. D.; Wilkinson, A. (1997). „poise”. IUPAC. Compendium of Chemical Terminology (the "Gold Book"). S. J. Chalk (2nd izd.). Oxford: Blackwell Scientific. ISBN 0-9678550-9-8. doi:10.1351/goldbook. 
• Mueller, S.; Llewellin, E. W.; Mader, H. M. (2009). „The rheology of suspensions of solid particles”. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 466 (2116): 1201—1228. ISSN 1364-5021. doi:10.1098/rspa.2009.0445 . 
• Nič, Miloslav; et al., ур. (1997). „dynamic viscosity, η”. IUPAC Compendium of Chemical Terminology. Oxford: Blackwell Scientific Publications. ISBN 978-0-9678550-9-7. doi:10.1351/goldbook. 
• Ojovan, M.I.; Lee, W.E. (2004). „Viscosity of network liquids within Doremus approach”. J. Appl. Phys. 95 (7): 3803—3810. Bibcode:2004JAP....95.3803O. doi:10.1063/1.1647260. 
• Ojovan, M.I.; Travis, K. P.; Hand, R.J. (2000). „Thermodynamic parameters of bonds in glassy materials from viscosity-temperature relationships” (PDF). J. Phys.: Condens. Matter. 19 (41): 415107. Bibcode:2007JPCM...19O5107O. PMID 28192319. doi:10.1088/0953-8984/19/41/415107. 
• Plumb, Robert C. (1989). „Antique windowpanes and the flow of supercooled liquids”. Journal of Chemical Education. 66 (12): 994. Bibcode:1989JChEd..66..994P. doi:10.1021/ed066p994. Архивирано из оригинала 26. 08. 2005. г. Приступљено 22. 02. 2021. 
• Reid, Robert C.; Sherwood, Thomas K. (1958). The Properties of Gases and Liquids. McGraw-Hill. 
• Reif, F. (1965), Fundamentals of Statistical and Thermal Physics, McGraw-Hill . An advanced treatment.
• Różańska, S.; Różański, J.; Ochowiak, M.; Mitkowski, P. T. (2014). „Extensional viscosity measurements of concentrated emulsions with the use of the opposed nozzles device” (PDF). Brazilian Journal of Chemical Engineering. 31 (1): 47—55. ISSN 0104-6632. doi:10.1590/S0104-66322014000100006. 
• Rumble, John R., ур. (2018). CRC Handbook of Chemistry and Physics (99th изд.). Boca Raton, FL: CRC Press. ISBN 978-1138561632. 
• Scherer, George W.; Pardenek, Sandra A.; Swiatek, Rose M. (1988). „Viscoelasticity in silica gel”. Journal of Non-Crystalline Solids. 107 (1): 14. Bibcode:1988JNCS..107...14S. doi:10.1016/0022-3093(88)90086-5. 
• Schroeder, Daniel V. (1999). An Introduction to Thermal Physics. Addison Wesley. ISBN 978-0-201-38027-9. 
• Sivashinsky, V.; Yakhot, G. (1985). „Negative viscosity effect in large-scale flows”. The Physics of Fluids. 28 (4): 1040. Bibcode:1985PhFl...28.1040S. doi:10.1063/1.865025. 
• Streeter, Victor Lyle; Wylie, E. Benjamin; Bedford, Keith W. (1998). Fluid Mechanics. WCB/McGraw Hill. ISBN 978-0-07-062537-2. 
• Sutherland, William (1893). „LII. The viscosity of gases and molecular force” (PDF). The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 36 (223): 507—531. ISSN 1941-5982. doi:10.1080/14786449308620508. Архивирано из оригинала (PDF) 20. 07. 2019. г. Приступљено 22. 02. 2021. 
• Symon, Keith R. (1971). Mechanics (3rd изд.). Addison-Wesley. ISBN 978-0-201-07392-8. 
• Trouton, Fred. T. (1906). „On the Coefficient of Viscous Traction and Its Relation to that of Viscosity”. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 77 (519): 426—440. Bibcode:1906RSPSA..77..426T. ISSN 1364-5021. doi:10.1098/rspa.1906.0038 . 
• Viswanath, D.S.; Natarajan, G. (1989). Data Book on the Viscosity of Liquids. Hemisphere Publishing Corporation. ISBN 0-89116-778-1. 
• Viswanath, Dabir S.; et al. (2007). Viscosity of Liquids: Theory, Estimation, Experiment, and Data. Springer. ISBN 978-1-4020-5481-5. 
• Xie, Hong-Yi; Levchenko, Alex (23. 1. 2019). „Negative viscosity and eddy flow of the imbalanced electron-hole liquid in graphene”. Phys. Rev. B. 99 (4): 045434. arXiv:1807.04770v2 . doi:10.1103/PhysRevB.99.045434. CS1 održavanje: Format datuma (veza)

• Yanniotis, S.; Skaltsi, S.; Karaburnioti, S. (februar 2006). „Effect of moisture content on the viscosity of honey at different temperatures”. Journal of Food Engineering. 72 (4): 372—377. doi:10.1016/j.jfoodeng.2004.12.017. CS1 održavanje: Format datuma (veza)
• Zhmud, Boris (2014). „Viscosity Blending Equations” (PDF). Lube-Tech:93. Lube. br. 121. str. 22—27. 

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