Non-Newtonian migration of a deformable drop in shearing flows

[摘要] The lateral migration of a deformable drop suspended in a unidirectional shearing flow of a slightly non-Newtonian fluid has been considered both theoretically and experimentally. Analytical expressions for the migration velocity due to the separate effects of drop deformation and fluid viscoelasticity were obtained for a two-dimensional flow, and then extended to the case of a general quadratic flow. The direction and magnitude of the migration velocity was calculated for the particular cases of Poiseuille flow in a tube and linear shear flow, and compared with experimental data.The Couette flow problem was studied experimentally. The size of the inner rotor of the Couette device was varied systematically to assess the role of velocity profile curvature on drop migration. Both deformation and non-Newtonian effects were considered. In all cases, the agreement between experimental results and theoretical predictions was very good. Significant observations that were not reported in previous studies include the migration of a deformable Newtonian drop to an equilibrium position between the centerline and the inner rotor, and the close competition between normal stress and shape deformation contributions for the case of a Newtonian drop in a non-Newtonian fluid.

[发布机构] University:California Institute of Technology;Department:Chemistry and Chemical Engineering

[关键词] Chemical Engineering