Creeping motion of spheres in fluid M1

V. Tirtaatmadja, P. H.T. Uhlherr, T. Sridhar

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Abstract

The drag force on spheres in creeping motion through fluid M1 has been measured. A slight reduction in drag to a minimum value of about 94% of the Newtonian value was observed for We greater than 0.1. At larger We the drag on the spheres increased monotonically with We, to a value of more than 20% above the Newtonian value at We greater than 1.6. This behaviour is consistent with the numerical predictions of Chilcott and Rallison, based on a FENE-dumbbell model with appropriate model parameters. The experimental results are in sharp contrast to those published for corn-syrup-based ideal elastic fluids in which a significant reduction in drag, to 75% of the Newtonian value, was observed. This reduction in drag occurred only when the first normal stress difference values were outside the quadratic region, while the experimental data on fluid M1 cover the range of shear rates in which N1 is quadratic. The influence of the container wall on the terminal velocity of spheres in the fluid M1 was found to be the same as that for Newtonian fluids. The Faxen wall correction factor can in fact be used to correct for wall effects up to a sphere-to-tube diameter ratio of 0.15.

Original languageEnglish
Pages (from-to)327-337
Number of pages11
JournalJournal of Non-Newtonian Fluid Mechanics
Volume35
Issue number2-3
DOIs
Publication statusPublished - 1 Jan 1990

Keywords

  • creeping flow
  • dropping spheres
  • test fluid M1
  • wall effects

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