ON THE INERTIAL AND EXTENSIONAL EFFECTS ON THE CORNER AND LIP VORTICES IN A CIRCULAR 4-1 ABRUPT CONTRACTION

An examination is presented of the effects of inertia on the circular abrupt contraction flow of generalized Newtonian and viscoelastic fluids, the extensional viscosity of which has been increased by means of a dependence on the fluid as well as the second invariants of the rate of deformation tensor. It is shown that the combination of inertia and elongational effects leads to the development of a small and strong lip vortex which may quickly envelop the stagnant corner vortex. On a macroscopic level, this phenomenon is also accompanied by an increase of the pressure drop. © 1990.