Drag on cylinders in shear thinning viscoelastic liquids

Abstract

In this work, the terminal falling velocities of a series of cylinders made of four different materials and encompassing length-to-diameter ratios varying from ∼0.5 to 10 have been measured in well-characterized non-Newtonian solutions. Five aqueous polymer solutions exhibiting varying levels of shear-thinning and viscoelasticity have been used as model tests fluids. Experimental results for freely falling cylinders are expressed in terms of a correction factor to be applied to the Stokes formula when the particle Reynolds number is small (<1). This correction for non-spherical shape seems to work well, a new correlation is presented to account for the role of shear-thinning and visoelastic characteristics. Within the range of conditions covered in this work, the terminal falling velocity is influenced primarily by shear dependent viscosity.