Particle tracking velocimetry and particle image velocimetry study of the slow motion of rough and smooth solid spheres in a yield-stress fluid

Yulia Holenberg, Olga M. Lavrenteva, Uri Shavit, Avinoam Nir

Research output: Contribution to journalArticlepeer-review

Abstract

We report experimental evidence of an effect opposite to the "solidification" of small bubbles in liquid where the surface can become immobile. Namely, it is demonstrated that smooth solid spheres falling in a yield-stress fluid under the action of gravity can behave similar to drops. Particle tracking velocimetry was used to determine the shape of the yielded region around solid spherical particles undergoing slow stationary motion in 0.07% w/w Carbopol gel due to gravity under creeping flow conditions. The flow field inside the yielded region was determined by particle image velocimetry. It was found that the shape of the yielded region and the flow field around slow-moving rough particles is similar to the published results of numerical simulations, whereas those around smooth spheres resemble the experimental results obtained for viscous drops. The effect was explained by a slip of the gel on the smooth surface. Most likely, the slip originated from seepage of clean water from the gel, forming a thin lubricating layer near the solid surface.

Original languageEnglish
Article number066301
Number of pages6
JournalPhysical Review A (General Physics)
Volume86
Issue number6
DOIs
StatePublished - 4 Dec 2012

All Science Journal Classification (ASJC) codes

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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