| Abstract: | An analysis is presented of the effects of external flow kinematics on the so-called local flow in seeded, flow-induced crystallization and orientation. The flow field around a growing crystal or nucleation seed is modelled by the Stokes flow equations past a prolate ellipsoid of high aspect ratio. Exact solutions for various flow kinematics, worked out elsewhere by the singularity method, are applied here to the analysis of local gradients. The results show that along the symmetry axis of the spheroid, the extensional gradients which result for various free-stream velocity fields are primarily the result of the constant-velocity free-stream component. However, free-stream, extensional flow can significantly enhance the region of such high gradients. Along the symmetry plane of the spheroid, primarily shearing gradients result, with small extensional gradients occurring when the free-stream flow has extensional components. Results of chain extension and birefringence calculations are also presented and discussed. |
