The angular velocity of a freely rotating sphere in a weakly viscoelastic matrix fluid

This letter reports on the angular velocity of a freely rotating rigid sphere in a weakly viscoelastic matrix fluid subject to simple shear flow imposed at infinity. The three-dimensional creeping flow around the sphere is assumed steady and isothermal. The solution for the angular velocity, which is derived here is the first available analytical result in the literature and is in accordance with the few existing experimental data and simulation results for non-Newtonian ambient fluids. We show that the rotation of the sphere is slower than in the Newtonian case, and that this phenomenon is at least a third-order fluid effect. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3583376]