RECOVERY AND STRESS-SPLITTING SCHEMES FOR VISCOELASTIC FLOWS

Various recovery and stress-splitting schemes are investigated numeric ally for an Oldroyd-B model within the general framework of a time ste pping fractional-staged finite element formulation: that of a Taylor-G alerkin/pressure-correction method with consistent streamline upwindin g. Smooth and non-smooth planar flows are cited and both creeping and inertial conditions are considered. Problems addressed include how thr ough 4:1 contraction geometries, with rounded or sharp re-entrant corn ers and flow past a cylinder. Vortex behaviour and scheme performance is analysed. The recovery-based schemes are stability enhancing, being superior in higher De attenuation over conventional and EVSS alternat ives. It is the recovery aspect and not the stress-splitting, that is the key element responsible for this improvement. Considerable care mu st be exercised with time-stepping schemes of the pressure-correction form to sustain accuracy and stability. (C) 1998 Elsevier Science B.V. All rights reserved.