Resonance behavior of viscoelastic fluids in Poiseuille flow and application to flow enhancement

Resonance-like phenomena in axisymmetric Poiseuille flows of viscoelastic f luids are studied. It is shown that instantaneous flow velocities of the up per convected Maxwell fluid with a spectrum of relaxation times drastically increase at certain frequencies of the oscillating pressure gradient, This effect becomes more pronounced as the. tube radius gets smaller. Non-linea r constitutive structures are also considered to show that the most effecti ve mean flow rate enhancement for pulsating flows can be reached at the res onance frequencies. (C) 1999 Elsevier Science Ltd. All rights reserved.