Effect of fibrils on curvature- and rotation-induced hydrodynamic stability
2013 (English)In: Acta Mechanica, ISSN 0001-5970, E-ISSN 1619-6937, Vol. 224, no 10, 2249-2261 p.Article in journal (Refereed) Published
Flow of a suspension of water and nano-fibrillated cellulose (NFC) in a curved and rotating channel is studied experimentally and theoretically. The aim is to investigate how NFC affects the stability of the flow. This flow is subject to a centrifugal instability creating counter-rotating vortices in the flow direction. These rolls can be both stabilised and destabilised by system rotation, depending on direction and velocity of the rotation. Flow visualisation images with pure water and an NFC/water suspension are categorised, and stability maps are constructed. A linear stability analysis is performed, and the effect of fibrils is taken into account assuming straight fibrils and constant orientation distributions, i.e., without time-dependent flow-orientation coupling. The results show that NFC has a less stabilising effect on the primary flow instability than indicated from the increase in viscosity measured by a rotary viscometer, but more than predicted from the linear stability analysis. Several unknown parameters (the most prominent being fibril aspect ratio and the interaction parameter in the rotary diffusion) appear in the analysis.
Place, publisher, year, edition, pages
2013. Vol. 224, no 10, 2249-2261 p.
Fiber Suspensions, Curved Channel, Flow, Particles, Stress, Motion, Orientation, Fluid
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-132202DOI: 10.1007/s00707-013-0929-8ISI: 000325008900003ScopusID: 2-s2.0-84885427892OAI: oai:DiVA.org:kth-132202DiVA: diva2:659366
QC 201310252013-10-252013-10-242014-10-03Bibliographically approved