English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Flows of dense emulsions show many complex features among which long rangenonlocal effects pose a problem for macroscopic characterization. In order toget around this problem, we study the flows of several dense emulsions in awide-gap Couette geometry. We couple macroscopic rheometric experiments andlocal velocity measurements through MRI techniques. As concentrationheterogeneities can be expected, we designed a method to measure the localdroplet concentration in emulsions with a MRI device. In contrast to densesuspensions of rigid particles where very fast migration occurs under shear, weshow that no migration takes place in dense emulsions even for strains as largeas 100 000 in our systems. As a result of the absence of migration and offinite size effect, we are able to determine very precisely the localrheological behavior of several dense emulsions. As the materials arehomogeneous, this behavior can also be inferred from purely macroscopicmeasurements. We thus suggest that properly analyzed purely macroscopicmeasurements in a wide-gap Couette geometry can be used as a tool to study thelocal constitutive laws of dense emulsions. All behaviors are basicallyconsistent with Herschel-Bulkley laws of index 0.5, but discrepancies exist atthe approach of the yield stress due to slow shear flows below the apparentyield stress in the case of a strongly adhesive emulsion. The existence of aconstitutive law accounting for all flows contrasts with previous resultsobtained within a microchannel by Goyon et al. (2008): the use of a wide-gapCouette geometry is likely to prevent here from nonlocal finite size effects;it also contrasts with the observations of B\'ecu et al. (2006).

physical review. e, statistical, nonlinear and soft matter physics

Wide-gap Couette flows of dense emulsions: Local concentration  measurements, and comparison between macroscopic and local constitutive law  measurements through magnetic resonance imaging