A COMPARISON OF THE DRAG COEFFICIENTS OF SPHERES TRANSLATING IN CORN-SYRUP-BASED AND POLYBUTENE-BASED BOGER FLUIDS

The drag force on spheres in uniform translation has been measured for two different non-shear-thinning elastic liquids. The drag force in the polyisobutylene-polybutene solutions obeyed Stokes' law for Weissenberg number (We) up to 0.3, then increased with further increasing We. The drag force in the polyacrylamide-corn syrup solution obeyed Stokes' law up to We = 0.1 but then decreased with further increasing We. This behavior is consistent with current theoretical predictions of Chilcott and Rallison based on an FENE model if the polyisobutylene molecular chains are much more extensible relative to their equilibrium lengths in polybutene than the polyacrylamide chains are in corn syrup. Measurements of intrinsic viscosity available in the literature for these two systems confirm that this is the case. © 1990.