68 research outputs found
Extensional viscosity: A critical discussion
No full textThe issue of whether extensional viscosity is a concept that causes more confusion than enlightenment is addressed. This author\u27s view is that misuse of the concept certainly has caused much confusion and, although it is in principle a simple and straightforward idea, it continues to be misused. What is straightforward is the formal definition of extensional viscosity, for steady uniform extensional flow. What gives rise to confusion is the careless use of measurements in flows which are not both steady and spatially uniform. \ua9 2006 Elsevier B.V. All rights reserved
Non-simple flows: a discussion arising from examination of whether exponential shear is properly described as a strong flow
No full textThe rheology of fibre suspensions
No full textWe review theoretical work on the rheology of fibre suspensions. We seek to clarify one or two confusions in published work and also give a small improvement to Batchelor\u27s formula for extensional viscosity of suspensions of long fibres between the dilute and semi-dilute regimes
One hundred years of extensional flow
No full textThis historical review takes a few selected issues from the rheological studies of extensional flow that fill the literature, starting with extracts from the seminal papers of Trouton [Proc. Roy. Soc. A 77 (1906) 426-440] and Fano [Archivio di fisiologio, 5 (1908) 365-370]. Work in the first half of the 20th century on spinnability and extensional viscosity measurement is highlighted, followed by a discussion of the blossoming of studies on extensional flow. As a case study, a project on anti-misting additives in aviation fuel is taken; whether the rheology or the politics is the more interesting is an open question. Finally some current issues surrounding spinnability and other extensional flow phenomena are discussed. \ua9 2006 Elsevier B.V. All rights reserved
Microfluidic systems for the analysis of the viscoelastic fluid flow phenomena in porous media
No full textIn this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/ expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application
Stories of transformation: Aboriginal offenders' journey from prison to the community
No full textThe article discusses the reintegration of Canadian Indigenous peoples into the community following their prison sentences in the Canadian Criminal Justice System (CJS), including through referencing the theory of desistance. An overview of the culture and spirituality of aboriginal ex-convicts is provided. Rehabilitation programs in Canada for aboriginal ex-convicts are discussed.Peer reviewedFinal article publishe
Electroviscous journal bearing for active control of vibration of an out-of-balance rotor
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