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Relevant bibliographies by topics / Viscosity modification

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Academic literature on the topic 'Viscosity modification'

Author: Grafiati

Published: 4 June 2021

Last updated: 7 February 2022

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Journal articles on the topic "Viscosity modification"

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Korobeinikov, Iurii, Anton Perminov, Tobias Dubberstein, and Olena Volkova. "Modification of Liquid Steel Viscosity and Surface Tension for Inert Gas Atomization of Metal Powder." Metals 11, no. 3 (March 23, 2021): 521. http://dx.doi.org/10.3390/met11030521.

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Inert gas atomization is one of the main sources for production of metal powder for powder metallurgy and additive manufacturing. The obtained final powder size distribution is controlled by various technological parameters: gas flow rate and pressure, liquid metal flow rate, gas type, temperature of spraying, configuration of nozzles, etc. This work explores another dimension of the atomization process control: modifications of the liquid metal properties and their effect on the obtained powder size. Series of double-alloyed Cr-Mn-Ni steels with sulfur and phosphorus were atomized with argon at 1600 °C. The results indicate that surface tension and viscosity modifications lead to yielding finer powder fractions. The obtained correlation is compared with the individual modification of surface tension with S and Se and modification of viscosity with phosphorus. Discrepancy of the results is discussed. Additives of surfactants and viscosity modifiers can be a useful measure for powder fractions control.

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Tout, Christopher A. "Accretion Disc Viscosity." International Astronomical Union Colloquium 158 (1996): 97–106. http://dx.doi.org/10.1017/s0252921100038343.

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AbstractWe review the various physical processes that could lead to viscosity in accretion discs. A local magnetic dynamo offers the most plausible mechanism and we discuss a simple model in some detail. The dynamo operates even in partially and very weakly ionized discs without much modification.

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Wang, Wen Yu, Xin Jin, Shuan Qing Hou, Yu Feng Zhang, and Xiao Xu Sha. "Effect of Acid Modification on the Properties of Potato Starch Pastes and Starch Film." Advanced Materials Research 287-290 (July 2011): 2648–51. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.2648.

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The effect of acid modification using 1mol/L HCl on viscosity, thermal properties and mechanical properties of potato starch pastes and starch film were investigated. After acid modification, the surface of starch granules did not show more roughness and viscosity of starch pastes become lower. The results of DSC indicated that acid should act on amorphous region of starch firstly and would act on the crystallization region with the longer treatment time. In the very close viscosity scope, the mechanical properties of starch films were increased obviously after acid modification.

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Honaker, R. Q., A. Das, and F. Boaten. "Slurry Viscosity Modification Effects on Classifying Cyclone Performance." Canadian Metallurgical Quarterly 46, no. 3 (September 2007): 341–47. http://dx.doi.org/10.1179/cmq.2007.46.3.341.

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He, Xingliang, Huaping Xiao, Jonathan P. Kyle, Elon J. Terrell, and Hong Liang. "Two-dimensional nanostructured Y2O3 particles for viscosity modification." Applied Physics Letters 104, no. 16 (April 21, 2014): 163107. http://dx.doi.org/10.1063/1.4873119.

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Chiu, Yuen-Yuen, Reiko Saito, and L. James Lee. "Modification of unsaturated polyester resins for viscosity control." Polymer 37, no. 11 (May 1996): 2179–90. http://dx.doi.org/10.1016/0032-3861(96)85863-0.

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Zaremba, Leszek Saturnin. "Modification of the viscosity solution and its application." Mathematical and Computer Modelling 11 (1988): 699–701. http://dx.doi.org/10.1016/0895-7177(88)90583-3.

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Evageliou, Vasiliki, Nataliya M. Ptitchkina, and Edwin R. Morris. "Solution viscosity and structural modification of pumpkin biopectin." Food Hydrocolloids 19, no. 6 (November 2005): 1032–36. http://dx.doi.org/10.1016/j.foodhyd.2005.01.004.

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Chen, Shuan Fa, Si Yue Zhu, Xian Tao Qin, and Zu Zhong Li. "Material Design and Property of High Viscosity Asphalt Used in Pervious Asphalt Pavement." Advanced Materials Research 753-755 (August 2013): 495–99. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.495.

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Dynamic viscosity, toughness and tenacity were used as the key indicators combined with conventional asphalt indicators such as ductility, penetration, softening point to evaluate the modification effect. The change laws of the indicators influenced by the dosages of polymer, compatilizer and stabilizer as well as the modification mechanism were analyzed; and the dosages of the three modifiers were determined. The results indicate that the modification effect is strongly influenced by the content of modifiers. Each of the modifiers plays a unique role in the performance the high viscosity asphalt. Through a particular modification technology, the optimum dosages of polymer, compatilizer and stabilizer used in self-modified high viscosity asphalt were determined at 7%, 3% and 2% respectively.

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Basilio-Cortés, Ulin, Leopoldo González-Cruz, Gonzalo Velazquez, Gerardo Teniente-Martínez, Carlos Gómez-Aldapa, Javier Castro-Rosas, and Aurea Bernardino-Nicanor. "Effect of Dual Modification on the Spectroscopic, Calorimetric, Viscosimetric and Morphological Characteristics of Corn Starch." Polymers 11, no. 2 (February 14, 2019): 333. http://dx.doi.org/10.3390/polym11020333.

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The effect of dual modification of corn starch, including hydrolysis and succinylation, were evaluated through peak viscosity (PV) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. This dual modification was shown to increase the reaction efficiency (RE) and degree substitution (DS) compared with starches that were not subjected to acid hydrolysis pretreatment with a 44% and 45% increase respectively. After acid hydrolysis pretreatment, the surface of the corn starch granules exhibited exo-erosion and whitish points due to the accumulation of succinyl groups. The peak viscosity was reduced significantly with the acid hydrolysis pretreatment (between 3 and 3.5-fold decrease), which decreased the pasting temperature and peak time to 20 °C and 100 s respectively. In addition, the dual modification of corn starch altered certain thermal properties, including a reduction in the enthalpy of gelatinization (ΔH) and a higher range of gelatinization (around 6 °C), which may effectively improve industrial applications. Modifications on the FTIR spectra indicated that the dual modification affected the starch crystallinity, while the Raman spectra revealed that the dual modification disrupted the short-range molecular order in the starch. Rearrangement and molecular destabilization of the starch components promoted their granular amphiphilic properties.

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Dissertations / Theses on the topic "Viscosity modification"

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Wong, Evelyn Yin-Yue. "Effect of viscosity modification by fiber dose and heat treatment on postprandial blood glucose response." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28882.pdf.

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Bukiet, Frédéric. "Influence de la modification de l'hypochlorite de sodium par adjonction de tensioactifs sur l'énergie interfaciale et la viscosité dynamique de la solution d'irrigation." Thesis, Montpellier 1, 2014. http://www.theses.fr/2014MON12201/document.

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La complexité anatomique de l'endodonte implique un protocole d'irrigation efficace. L'hypochlorite de sodium doit donc pouvoir pénétrer dans l'ensemble du réseau endodontique afin d'exercer son activité antiseptique et protéolytique. Dans cet objectif, l'utilisation d'un tensioactif mélangé à l'hypochlorite de sodium constitue une approche potentiellement intéressante pour optimiser la pénétration et l'étalement de l'hypochlorite de sodium au sein du système canalaire. Cette thèse sur publications a donc pour objectif d'étudier l'influence de la modification de l'hypochlorite de sodium par adjonction de tensioactifs sur l'énergie interfaciale et la viscosité dynamique de la solution d'irrigation. Le premier chapitre décrit les enjeux, les différentes problématiques liées à l'irrigation ainsi qu'une revue de littérature critique des différentes techniques d'irrigation disponibles. Le second chapitre se focalise sur les propriétés physico-chimiques des solutions d'irrigation et sur des aspects plus spécifiquement liés à l'hydrodynamique et au mouillage des liquides et en particulier les notions d'énergie interfaciale, de concentration micellaire critique, de viscosité dynamique et de régime d'écoulement. Après une synthèse des aspects théoriques et des implications potentielles en endodontie, l'ensemble des matériels et méthodes expérimentales est détaillé dans le troisième chapitre. Le quatrième chapitre décrit l'influence de l'adjonction d'un tensioactif sur le mouillage de la solution d'irrigation sur la base d'une étude préliminaire et d'études complémentaires ayant abouti à une première publication internationale. Le cinquième chapitre décrit l'influence de l'adjonction d'un tensioactif sur l'écoulement de la solution d'irrigation, cette étude ayant débouché sur une seconde publication internationale. Enfin, le sixième chapitre constitue la conclusion de ce travail et les perspectives de recherche sur la thématique
The complexity of the root canal anatomy requires an efficient irrigation protocol. Sodium hypochlorite must penetrate in the whole of the endodontic system in order to be strongly active in terms of antiseptic and solvant properties. Therefore, the use of surfactants mixed to sodium hypochlorite is a promising approach to enhance the penetration depth and the spreading of endodontic irrigant within the root canal. The purpose of this thesis based on two international publications is to study the influence of surfactant addition to sodium hypochlorite on its surface tension and dynamic viscosity. The first chapter describes the different stakes, issues and irrigation techniques thanks to a critical review of the literature. The second chapter focuses on hydrodynamics and wetting properties especially surface energy, critical micellar concentration, dynamic viscosity and flow regimen. After a description of the theoretical aspects and the potential applications in root canal therapy, all the materials and methods used in this thesis are detailed in the third chapter. The fourth chapter describes the influence of surfactant addition on the wettability of endodontic irrigant on the basis of a preliminary study and several additional studies that led to a first international publication. The fifth chapter describes the influence of surfactant addition on the dynamic viscosity of endodontic irrigant and its flow regimen on the basis of a study which led to a second international publication.The final chapter of this thesis constitues the conclusion of this work and the associated prospects regarding this topic

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Servant, Sylvie. "Variabilité des propriétés physico-chimiques d'exsudats d'Acacia senegal (gomme arabique) d'une plantation expérimentale au Ferlo (Sénégal). Modification des chaînes." Rouen, 1994. http://www.theses.fr/1994ROUES045.

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La gomme arabique exsudée par Acacia senegal est un polymère naturel hétéropolymoléculaire parfaitement hydrophile. L'étude physico-chimique d'exsudats d'Acacia senegal, bien identifiés botaniquement, issus de populations artificielles du Nord Ferlo (Sénégal) permet d'établir la variabilité des valeurs de viscosité, de pouvoir rotatoire et de teneur en azote. Nous avons cherché des corrélations des différents paramètres entre eux et des paramètres physico-chimiques avec les conditions climatiques et édaphotopographiques de la gommeraie. Afin d'améliorer les propriétés émulsifiantes de la gomme arabique, nous avons modifié chimiquement ses chaînes en accentuant le caractère hydrophobe. La caractérisation des produits greffés et de la gomme arabique a été réalisée par des mesures de tension superficielle, de conductimétrie et de viscosimétrie de cisaillement. De même, le comportement en émulsion de chacune des gommes a été étudié

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Sinquin, Anne. "Alginates associatifs : synthèse et étude physico-chimique en milieu aqueux." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL035N.

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La synthèse de polymères hydrosolubles présentant un caractère associatif a été effectuée, par réaction de diverses alkylamines à chaine longue (Cn-NH2, 8≤n≤16) sur l'alginate de propylène glycol (PGA), un dérivé partiellement estérifié d'un polysaccharide extrait des algues. Les propriétés physico-chimiques des dérivés hydrophobisés résultants ont été étudiées, comparativement à celles des polymères parents, en rhéologie, en spectrophotométrie de fluorescence et par des mesures de tension superficielle, dans l'eau pure ou en présence de sels. De façon générale, on observe que le caractère associatif des dérivés synthétisés augmente avec le taux et la longueur des segments hydrophobes immobilisés sur le PGA. Ainsi, si les effets d'interactions hydrophobes ne sont pas mis en évidence pour le dérivé en C8, les dérivés hydrophobisés par des chaines alkyles longues (C12 et C14) présentent, quant à eux, d'importantes variations de comportement par rapport aux polymères parents. Celles-ci résultent de la mise en place d'interactions hydrophobes entre les chaines alkyles immobilisées sur le squelette polysaccharidique. Ces interactions sont essentiellement de nature intramoléculaire en solution diluée tandis que les associations intermoléculaires deviennent prépondérantes en régime semi-dilué. Des entités de volume hydrodynamique élevé apparaissent alors et conduisent à une augmentation spectaculaire de la viscosité, pouvant aller jusqu'à la formation d'un réseau tridimensionnel ayant une structure de gel physique

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Lunt, Phillip E. "Heating Protocol for the Construction of a Statistical Model Predicting the Texture Parameters of Commercially Available Baby Foods." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami15874852673775.

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Girard, Rémi. "Etude des modifications des propriétés de surface des verres d’oxydes par traitements thermiques : application à la guérison des fissures." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20191/document.

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La durabilité des verres, leur réactivité ou leur fonctionnalisation peuvent être optimisées en modifiant leur état de surface, ouvrant ainsi la voie à de nouvelles applications. L'objectif de cette thèse est de mieux appréhender les modifications induites à la surface et à la sub-surface des verres d'oxydes, ainsi que l'évolution des micro-défauts existant à leur surface au cours de traitements thermiques. Ces traitements sont réalisés autour de la température de transition vitreuse, mais à des températures où le verre ne se déforme pas. Cette étude met en évidence l'influence cruciale de l'atmosphère de traitement. Elle porte principalement sur le cas du verre « float », en distinguant les faces « air » et « étain ».En s'appuyant sur les spectroscopies SIMS et Infrarouge, l'étude montre que les modifications de la sub-surface du verre dépendent de la teneur en eau de l'atmosphère du four. Alors que la sub-surface, initialement hydratée, est peu modifiée lorsque le taux d'humidité est élevé, les changements les plus significatifs sont observés sous atmosphère sèche. La déshydratation de la sub-surface du verre induit en effet la création d'une couche enrichie en silice par appauvrissement en ions modificateurs.Pour caractériser l'influence de ces modifications sur l'évolution de la morphologie des micro-défauts de surface au cours des traitements thermiques, des micro-fissures sont générées par indentation Vickers puis analysées par microscopies optique et électronique. Deux mécanismes sont mis en évidence : soit une fermeture des fissures dans les premiers instants du traitement sous l'effet de la relaxation des contraintes, soit une sphéroïdisation des fissures par flux visqueux induit par les forces tensions capillaires. Ces mécanismes sont en compétition et dépendent de l'état initial de la sub-surface du verre. En effet, la viscosité de cette sub-surface est fortement dépendante de son taux d'hydratation et peut varier très significativement au cours du traitement thermique. Dans le cas de la face « étain » du verre float, l'influence du caractère oxydant de l'atmosphère est également mis en évidence
The glass durability, its reactivity or its functionalization can be optimized by surface modification, allowing development of new applications. The aim of this thesis is to better understand the changes induced at the oxide glass surface and sub-surface and the evolution of surface micro-flaws during thermal treatment.These treatments are performed around glass transition temperature, but at temperatures at which the samples are not deformed. The key role of the atmosphere of treatment is especially highlighted. Analyses focused on the float glass both on the “air side” and “tin side”.Based on SIMS and infrared spectroscopies, results show that the sub-surface changes depend on the water content of the furnace atmosphere. While the sub-surface, initially hydrated, is not strongly modified when the humidity level is high, significant changes are induced under dry atmosphere. The dehydration of the sub-surface induces indeed the formation of a silica enriched layer by impoverishment of modified ions.In order to characterize the influence of these changes on the evolution of micro-flaws morphology during thermal treatments, micro-cracks are generated by Vickers indentation and analyzed by optical and electronic microcopies. Two main behaviors are evidenced: either a direct crack closure during the first step of the thermal treatment due to stress relaxation or a crack spheroidization caused by viscous flow driven by capillarity forces. Both mechanisms are in competition and depend on the initial state of the glass sub-surface. The viscosity of this layer is highly dependent on the hydration level and can vary significantly during the treatment. In case of “tin side” of float glass, the effect of oxidant atmosphere is also evidenced

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Horvat, Frank E. "A Numerical and Experimental Investigation for the Modification and Design of a Gerolor Using Low Viscoscity Fluids." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342585429.

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Mhaoud, Nadia. "Rôle des triglycérides sur les modifications des propriétés rhéologiques microscopiques et moléculaires de l'hématie humaine." Nancy 1, 1990. http://www.theses.fr/1990NAN10546.

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Rey-Valette, Hélène. "Modifications hémorhéologiques au cours de l'hypertension artérielle et rôle des antihypertenseurs sur la rhéologie sanguine." Bordeaux 2, 1991. http://www.theses.fr/1991BOR23007.

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Martelli, Luca. "Studio delle proprietà reologiche di leganti bituminosi modificati ad "alta lavorabilità" mediante Dynamic Shear Rheometer." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2009/.

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Books on the topic "Viscosity modification"

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Wong, Evelyn Yin-Yue. Effect of viscosity modification by fiber dose and heat treatment on postprandial blood glucose response. Ottawa: National Library of Canada = Bibliothèque nationale du Canada, 1999.

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Haggett, R. D. Modification of the Gerin falling ball viscosity comparator model V3 for use at the standard test temperature of 100oC. Dartmouth, N.S: Defence Research Establishment Atlantic, 1989.

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Rajeev, S. G. The Navier–Stokes Equations. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805021.003.0003.

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When different layers of a fluid move at different velocities, there is some friction which results in loss of energy and momentum to molecular degrees of freedom. This dissipation is measured by a property of the fluid called viscosity. The Navier–Stokes (NS) equations are the modification of Euler’s equations that include this effect. In the incompressible limit, the NS equations have a residual scale invariance. The flow depends only on a dimensionless ratio (the Reynolds number). In the limit of small Reynolds number, the NS equations become linear, equivalent to the diffusion equation. Ideal flow is the limit of infinite Reynolds number. In general, the larger the Reynolds number, the more nonlinear (complicated, turbulent) the flow.

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Escudier, Marcel. Basic equations of viscous-fluid flow. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198719878.003.0015.

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In this chapter it is shown that application of the momentum-conservation equation (Newton’s second law of motion) to an infinitesimal cube of fluid leads to Cauchy’s partial differential equations, which govern the flow of any fluid satisfying the continuum hypothesis. Any fluid flow must also satisfy the continuity equation, another partial differential equation, which is derived from the mass-conservation equation. It is shown that distortion of a flowing fluid can be split into elongational distortion and angular distortion or shear strain. For a Newtonian fluid, the normal and shear stresses in Cauchy’s equations are related to the elongational and shear-strain rates through Stokes’ constitutive equations. Substitution of these constitutive equations into Cauchy’s equations leads to the Navier-Stokes equations, which govern steady or unsteady flow of a fluid. A minor modification of the constitutive equations for a Newtonian fluid allows consideration of generalised Newtonian fluids, for which the viscosity depends upon the shear-strain rates. The boundary conditions for the tangential and normal velocity components are discussed briefly.

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Book chapters on the topic "Viscosity modification"

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Sivaramakrishnan, Kaushik, Arno de Klerk, and Vinay Prasad. "Viscosity of Canadian Oilsands Bitumen and Its Modification by Thermal Conversion." In ACS Symposium Series, 115–99. Washington, DC: American Chemical Society, 2019. http://dx.doi.org/10.1021/bk-2019-1320.ch006.

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Yambangwai, D., S. Suantai, H. Dutta, and W. Cholamjiak. "Viscosity Modification with Inertial Forward-Backward Splitting Methods for Solving Inclusion Problems." In Mathematical Methods and Modelling in Applied Sciences, 147–75. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43002-3_14.

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Konupek, Jiří. "The Influence of Modification of Particle Size of Ceramic Suspensions Upon their Apparent Viscosity." In Third European Rheology Conference and Golden Jubilee Meeting of the British Society of Rheology, 274–76. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0781-2_96.

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Grunberg, Dogan, Mert Arca, Dan Vargo, Sevim Z. Erhan, and Brajendra K. Sharma. "Use of Polymers in Viscosity Index Modification of Mineral Oils and Pour Point Depression of Vegetable Oils." In Surfactants in Tribology, Volume 5, 61–89. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2017. http://dx.doi.org/10.1201/9781315120829-6.

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Thuresson, K., S. Nilsson, and B. Lindman. "Effects on phase behaviour and viscosity of hydrophobic modification of a nonionic cellulose ether. influence of cosolutes." In Cellulose and Cellulose Derivatives, 323–29. Elsevier, 1995. http://dx.doi.org/10.1533/9781845698539.4.323.

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Eltze, Lara, Maren Eltze, and Antonio Garcia. "Variability of Saliva Viscosity - Potential Impact." In In Vitro Diagnostics [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93933.

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As novel COVID-19 testing develops, saliva has become of increasing interest as an alternate biological sample for rapid testing. The appeal in saliva-based testing lies within the ease of which samples are collected, as well as patient comfort throughout the collection process. With this, it has become increasingly important to delineate the characteristics of saliva viscosity due to its effects on the movement and interactions of the substances and molecules found within it. The characteristics that affect saliva viscosity include the presence of aggregates, variations in temperature, and time elapsed between sample collection and testing. Understanding how physicochemical properties and temperature affect saliva’s viscosity are important in generating guidelines for proper sample handling in saliva testing to ensure consistent and reliable results. In this study, passive sampling of saliva was analyzed. This type of collection ensures a more uniform saliva composition, suggesting that variations in viscosity can be attributed solely to modifications in saliva handling post-collection. The data suggested that saliva viscosity is greatest immediately following collection of the saliva sample, increases with higher quantities of aggregates in saliva, and decreases tremendously when the sample has been frozen and thawed to room temperature. These findings suggest that to ensure accuracy and uniformity in quantitative saliva-based test results, protocols should favor the testing of a sample immediately following its collection. The implications of these results in optimizing saliva testing are far reaching. The value of saliva based testing extends far beyond COVID-19 or other disease testing. It is also gaining utility in understanding daily fluctuations in hydration state and in other wellness applications.

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Gray, William G., and Michael A. Celia. "Incorporation of Interfacial Areas in Models of Two-Phase Flow." In Vadose Zone Hydrology. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195109900.003.0006.

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The mathematical study of flow in porous media is typically based on the 1856 empirical result of Henri Darcy. This result, known as Darcy’s law, states that the velocity of a single-phase flow through a porous medium is proportional to the hydraulic gradient. The publication of Darcy’s work has been referred to as “the birth of groundwater hydrology as a quantitative science” (Freeze and Cherry, 1979). Although Darcy’s original equation was found to be valid for slow, steady, one-dimensional, single-phase flow through a homogeneous and isotropic sand, it has been applied in the succeeding 140 years to complex transient flows that involve multiple phases in heterogeneous media. To attain this generality, a modification has been made to the original formula, such that the constant of proportionality between flow and hydraulic gradient is allowed to be a spatially varying function of the system properties. The extended version of Darcy’s law is expressed in the following form: qα=-Kα . Jα (2.1) where qα is the volumetric flow rate per unit area vector of the α-phase fluid, Kα is the hydraulic conductivity tensor of the α-phase and is a function of the viscosity and saturation of the α-phase and of the solid matrix, and Jα is the vector hydraulic gradient that drives the flow. The quantities Jα and Kα account for pressure and gravitational effects as well as the interactions that occur between adjacent phases. Although this generalization is occasionally criticized for its shortcomings, equation (2.1) is considered today to be a fundamental principle in analysis of porous media flows (e.g., McWhorter and Sunada, 1977). If, indeed, Darcy’s experimental result is the birth of quantitative hydrology, a need still remains to build quantitative analysis of porous media flow on a strong theoretical foundation. The problem of unsaturated flow of water has been attacked using experimental and theoretical tools since the early part of this century. Sposito (1986) attributes the beginnings of the study of soil water flow as a subdiscipline of physics to the fundamental work of Buckingham (1907), which uses a saturation-dependent hydraulic conductivity and a capillary potential for the hydraulic gradient.

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Agostinacchio, M., D. Ciampa, and S. Olita. "Zero shear viscosity evaluation of PMB bituminous binders with different levels of polymer modifications." In Pavement and Asset Management, 567–74. CRC Press, 2019. http://dx.doi.org/10.1201/9780429264702-68.

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Conference papers on the topic "Viscosity modification"

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Lee, S., and N. D. Spencer. "Influence of Surface Modification on Aqueous Lubrication of Elastomers." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63234.

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Water is generally not an efficient lubricant for most tribosystems due to its extremely low pressure-coefficient of viscosity. This barrier is less important, however, when elastomers are employed as tribopairs, since a low-pressure, conformal contact is readily achieved under these conditions, and thus the isoviscous-elastic lubrication (or soft elastohydrodynamic lubrication, “soft EHL”) mechanism can be activated. Isoviscous-elastic lubrication does not necessitate the increase of viscosity under pressure. The aqueous lubrication of elastomers, however, requires a careful control of surface properties of tribopairs since hydrophobic interactions between the sliding surfaces in water can result in the failure of lubricating films to form at low sliding speeds. In this context, we have investigated the influence of surface modification of an elastomer, poly(dimethylsiloxane) (PDMS), on its aqueous lubrication properties. A dramatic reduction in frictional forces has been observed upon hydrophilization by oxygen-plasma treatment when PDMS was slid against PDMS in an aqueous environment. A similar effect was also observed when the PDMS surface was coated with a variety of copolymers that possess amphiphilic characteristics. This effect is attributed to the removal of the strong hydrophobic interaction between PDMS surfaces in water, thereby enabling the soft EHL mechanism to predominate. This study demonstrates the significance of surface modification in allowing effective soft EHL of an elastomer to take place.

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Jayaprakash, Arvind, Kartikeya Mahalatkar, Urmila Ghia, and Karman Ghia. "Improvement in Numerical Prediction of Cavitating Flows Over Various 2D Geometries Using Modification to the Turbulence Model." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37684.

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Cavitation often causes performance breakdown and damage. So, it is very essential to accurately predict and control this phenomenon. In the present study, the unsteady effects associated with cavitation are investigated for various geometries including a NACA 0015 hydrofoil, a convergent-divergent nozzle, and a wedge, using the flow solver FLUENT. The turbulent viscosity and/or the turbulence dissipation in the k-epsilon turbulence model are modified. The cavitation phenomenon is represented based on the full cavitation model developed by Singhal et al. (2002), and it considers the liquid-vapor mixture as a homogeneous fluid whose density varies with respect to the static pressure and whose mass fraction is known in advance. Also, this model takes into account the formation and collapse of the vapor bubbles. The k-epsilon model was originally developed for fully incompressible fluids, and does not account for highly compressible two-phase mixtures. Hence, it has been found to be unsatisfactory for predicting cavitating flow in presence of high compressibility in the vapor region. Coutier-Delgosha et al. (2001) attributed this to the over-prediction of eddy viscosity in regions of flow with high vapor concentration, and suggested a modification for the calculation of eddy viscosity. Though the modification works in capturing the dynamic behavior of the cavitation sheet, the accuracy of cavity length and frequency are not accurately predicted for high cavitation numbers. This is due to inability of Coutier-Delgosha’s turbulence modification to completely account for all the complex flow features present in the cavity closure region. Thus, a further modification based on geometry and cavitation type is introduced in the turbulence modification of Coutier-Delgosha. Better results were obtained for moderate cavitation numbers, but this modification failed to accurately predict the frequency of vapor-cloud shedding at high cavitation numbers. This discrepancy is attributed to the large (40000:1) variation of density in the liquid-vapor region. Hence, a new modification is suggested in the present work where the closure coefficients of dissipation production (C1epsilon) and dissipation (C2epsilon) in the turbulent dissipation equation are dynamically varied in the liquid-vapor region. A User-Defined Function (UDF) is implemented in FLUENT to achieve this dynamic variation of the above mentioned closure coefficients. This modification is being tested to predict the time-averaged cavity length and vapor-cloud shedding frequency of cavitating flow over a NACA 0015 airfoil. The poster will present comparisons of cavity length and vapor-cloud shedding frequency over a wide range of cavitation numbers as predicted by the present and previous turbulence modifications and those observed in experimental studies.

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Li, Weihong, Li Yang, Jing Ren, and Hongde Jiang. "Algebraic Anisotropic Eddy Viscosity Model for Separated Flows of Internal Cooling Channels." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25591.

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A new algebraic anisotropic eddy viscosity model (AEVM) is developed to account for the anisotropic characteristics of flow fields for internal cooling channels in a gas turbine. The model consist of two parts: k and ε near wall modeling are improved to obtain precise near wall turbulent characteristics and eddy viscosity; anisotropic ratios are derived to account for anisotropy and further modify the normal Reynolds stresses by combining implicit algebraic stress model and isotropic eddy viscosity model. The new algebraic anisotropic eddy viscosity model is validated in two cases: 1) flow prediction of backward facing step, better results are obtained especially turbulent quantities, 2) flow and heat transfer predictions of internal channels with ribs, numerical reattachment length after each rib is more close to the measured value after anisotropic modification, and heat transfer prediction accuracy is increased by 6–10%. Results indicate the present model can be applied to flow and heat transfer prediction of separated flows in internal cooling channels efficiently.

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Rubinstein, Robert, and Ye Zhou. "Turbulence Modeling for the Axially Rotating Pipe From the Viewpoint of Analytical Closures." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45328.

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A single-point model eddy viscosity model of rotation effects on the turbulent flow in an axially rotating pipe is developed based on two-point closure theories. Rotation is known to impede energy transfer in turbulence; this fact is reflected in the present model through a reduced eddy viscosity, leading to laminarization of the mean velocity profile and return to a laminar friction law in the rapid rotation limit. This model is compared with other proposals including linear redistribution effects through the rapid pressure-strain correlation, Richardson number modification of the eddy viscosity in a model of non-rotating turbulence, and the reduction of turbulence through the suppression of near-wall production mechanisms.

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Elkhoury, Michel. "An Improved Wall-Distance-Free Version of the Baldwin-Barth Turbulence Model." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-55080.

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This paper presents a modified version of the Baldwin-Barth (BB) turbulence model. This modification accounts for the asymptotic boundary value of the pseudo eddy viscosity as the wall is approached. The BB Model tends to respond strongly to an adverse pressure gradient, in the sense that it always predicts a large decrease in skin friction relative to the measured values. Hence, in the present work, the importance of the modifications for improving the skin friction prediction of flows with adverse pressure gradient is addressed. All of the implemented modifications are free of wall functions and coordinate independent, which renders the model advantageous relative to other wall dependent models. The results are compared with both the original BB and the Spalart-Allmaras (SA) models. The accuracy of these and the present model is assessed against experimental data for transonic flows over NACA-0012 and RAE 2822 airfoils. In general, good agreement with experiments is indicated.

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Jiang, Guo, Kai Liao, Juan-Juan Han, De-Xian Feng, and Han-Xiong Huang. "Rheological Behavior and Microstructure of Flame Retardant Polypropylene Composites." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38052.

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Polypropylene (PP)/magnesium hydroxide (MDH) composite was melt-mixed using a twin-screw extruder. Two types of MDH were used, one with the modification of silane and another without. The rheological behavior was measured by capillary and dynamical rheometer. Microstructure of these composites was observed by SEM. Their flame retardancy was characterized by oxygen index and Horizontal/Vertical burning test. Results showed that shear viscosity and complex viscosity of PP with modified MDH were lower than that of PP with non-modified MDH. SEM results also showed a better dispersion of silane modified MDH in PP matrix. With the increase of MDH content, the oxygen index of composites was increased. When the content was increased to 60 wt%, the composite was UL94 HB and V-1.

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Ojovan, Michael, Guenter Mo¨bus, Jim Tsai, Stuart Cook, and Guang Yang. "On Fluidization of Borosilicate Glasses in Intense Radiation Fields." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16055.

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The viscosity is rate-limiting for many processes in glassy materials such as homogenisation and crystallisation. Changes in the viscous flow behaviour in conditions of long-term irradiation are of particular interest for glassy materials used in nuclear installations as well as for nuclear waste immobilising glasses. We analyse the viscous flow behaviour of oxide amorphous materials in conditions of electron-irradiation using the congruent bond lattice model of oxide materials accounting for the flow-mediating role of broken bonds termed configurons. An explicit equation of viscosity was obtained which is in agreement with experimental data for non-irradiated glasses and shows for irradiated glasses, first, a significant decrease of viscosity, and, second, a stepwise reduction of the activation energy of flow. An equation for glass-transition temperature was derived which shows that irradiated glasses have lower glass transition temperatures. Intensive electron irradiation of glasses causes their fluidisation due to non-thermal bond breaking and can occur below the glass transition temperature. Due to surface tension forces fluidisation of glasses at enough high electron flux densities can result in modification of nano-size volumes and particles such as those experimentally observed under TEM electron beams.

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Gong, Shen, Zhenghong Zhu, and Jun Li. "Characterization of Electrical Conductivity of Carbon Nanotube Composites." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38596.

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This work investigated and characterized the electrical conductivity of carbon nanotubes (CNT)/polymer composites. Surface modification has been applied to improve the homogeneous dispersion of MWCNTs in epoxy. After treatment, MWCNTs were mixed into low viscosity epoxy matrix at room temperature. Dispersion and structural integrity of MWCNTs before and after surface modification were examined by SEM images. The dispensability of treated MWCNTs and electrical conductivity of nanocomposites are evaluated and also compared with MWCNTs/polymer composites in literature prepared using the same commercial MWCNTs. The electrical conductivity of MWCNTs and MWCNTs/epoxy composites were evaluated by the four-point probe method. The results of electrical property will lay a foundation for establishing the relationship between electrical resistance and strain of MWCNTs/epoxy composites. The results also confirm that reducing CNT agglomerate size can greatly improve the electrical conductivity of composite and decrease the percolation threshold.

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Šernas, Ovidijus, Donatas Čygas, Audrius Vaitkus, and Vytautė Gumauskaitė. "The Influence of Crumb Rubber on Modified Bitumen Properties." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.147.

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Rubber derived from grinding of recycled cars and trucks tyres may be successfully used as a bitumen modifier. Number of researches reported sufficient characteristics of rubber modified asphalt binders or modified asphalt mixes in terms of improved permanent deformation and fatigue cracking. The behavior of crumb rubber asphalt binders depends on several factors, such as modification method, rubber content and size, modification temperature, mixing speed and time applied during the digestion process. The aim of this study is to evaluate the effect of crumb rubber amount and type on modified bitumen low and high temperature properties. This paper presents results of unmodified bitumen, crumb rubber crumb rubber and polymer modified bitumen. Low and high temperature properties have been evaluated using bending beam rheometer and dynamic shear rheometer. Moreover, softening point and viscosity tests have been performed. The study results revealed that crumb rubber modified bitumen performed better than pure bitumen and similarly to polymer modified bitumen.

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Bayada, G., L. Chupin, and S. Martin. "From 3-D OLROYD-B PTT Models to 2-D Thin Film Non Newtonian Laws." In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41045.

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The PTT-OLROYD-B model for solute-solvent mixtures introduces visco elastic effects by way of five parameters, namely Deborah number De, a viscosity ratio r, a viscosity, a parameter related to the convected derivation and an elongation parameter κ. Asymptotic expansion is used to gain a description of the flow in the thin film situation. Two cases are considered depending of the relative magnitude of the parameters De and κ with respect to the thickness ratio. In the first situation, the elongation effects disappear at the limits and the constitutive law of the film flow is a double Newtonian Rabinowisch model whose parameters are completely described by those of the original 3-D model. In the second case in which the elongation parameter is of order zero with respect of the film thickness ratio, however small, a perturbation procedure allows to retain this parameter in the asymptotic constitutive law. This law appears to be a small modification of the double Newtonian Rabinowisch law. Last a new numerical procedure is proposed. Numerical examples will be presented for 3-D flows.

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