Show simple item record

dc.contributorVirginia Techen_US
dc.contributor.authorWilliams, Alicia M.en_US
dc.contributor.authorVlachos, Pavlos P.en_US
dc.date.accessioned2014-04-24T18:34:11Z
dc.date.available2014-04-24T18:34:11Z
dc.date.issued2011-12-01
dc.identifier.citationWilliams, Alicia M.; Vlachos, Pavlos P., "dispersion of ferrofluid aggregates in steady flows," Phys. Fluids 23, 127102 (2011); http://dx.doi.org/10.1063/1.3670012
dc.identifier.issn1070-6631
dc.identifier.urihttp://hdl.handle.net/10919/47618
dc.description.abstractUsing focused shadowgraphs, we investigate steady flows of a magnetically non-susceptible fluid interacting with ferrofluid aggregates comprised of superparamagnetic nanoparticles. The ferrofluid aggregate is retained at a specific site within the flow channel using two different applied magnetic fields. The bulk flow induces shear stresses on the aggregate, which give rise to the development of interfacial disturbances, leading to Kelvin-Helmholtz (K-H) instabilities and shedding of ferrofluid structures. Herein, the effects of bulk Reynolds number, ranging from 100 to 1000, and maximum applied magnetic fields of 1.2 x 10(5) and 2.4 x 10(5) A/m are investigated in the context of their impact on dispersion or removal of material from the core aggregate. The aggregate interaction with steady bulk flow reveals three regimes of aggregate dynamics over the span of Reynolds numbers studied: stable, transitional, and shedding. The first regime is characterized by slight aggregate stretching for low Reynolds numbers, with full aggregate retention. As the Reynolds number increases, the aggregate is in-transition between stable and shedding states. This second regime is characterized by significant initial stretching that gives way to small amplitude Kelvin-Helmholtz waves. Higher Reynolds numbers result in ferrofluid shedding, with Strouhal numbers initially between 0.2 and 0.3, wherein large vortical structures are shed from the main aggregate accompanied by precipitous decay of the accumulated ferrofluid aggregate. These behaviors are apparent for both magnetic field strengths, although the transitional Reynolds numbers are different between the cases, as are the characteristic shedding frequencies relative to the same Reynolds number. In the final step of this study, relevant parameters were extracted from the time series dispersion data to comprehensively quantify aggregate mechanics. The aggregate half-life is found to decrease as a function of the Reynolds number following a power law curve and can be scaled for different magnetic fields using the magnetic induction at the inner wall of the vessel. In addition, the decay rate of the ferrofluid is shown to be proportional to the wall shear rate. Finally, a dimensionless parameter, which scales the inertia-driven flow pressures, relative to the applied magnetic pressures, reveals a power law decay relationship with respect to the incident bulk flow. (C) 2011 American Institute of Physics. [doi:10.1063/1.3670012]
dc.format.mimetypeapplication/pdfen_US
dc.language.isoen_US
dc.publisherAIP Publishing
dc.subjectLocoregional cancer-treatmenten_US
dc.subjectNormal field instabilityen_US
dc.subjectMagnetic fluidsen_US
dc.subjectCircular-cylinderen_US
dc.subjectBiodistributionen_US
dc.subjectMitoxantroneen_US
dc.subjectTransporten_US
dc.subjectSelectionen_US
dc.subjectObliqueen_US
dc.subjectCarrieren_US
dc.titleDispersion of Ferrofluid Aggregates in Steady Flowsen_US
dc.typeArticleen_US
dc.identifier.urlhttp://scitation.aip.org/content/aip/journal/pof2/23/12/10.1063/1.3670012
dc.date.accessed2014-04-04
dc.title.serialPhysics of Fluids
dc.identifier.doihttps://doi.org/10.1063/1.3670012
dc.type.dcmitypeTexten_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record