Studies on Contraction Flows and Pressure-Drops—Extensional Viscosity and Dissipative Stress Effects

摘要

In this paper, we explore the ability of network-type models (Phan-Thien/Tanner PTT) to reflect enhanced pressure drops in contraction/expansion flows (ratio 4:1:4). Severe strain hardening is captured through suitable parametric control, whilst ensuring strong suppression of shear-thinning properties, to approximate those of typical solvent-dominated Boger fluids. This advances upon our prior work with Oldroyd models. The position is further contrasted against that for dissipative stress models, where both inelastic and viscoelastic models are introduced with some interesting consequences. The numerical techniques adopted follow a hybrid finite element/volume algorithm of incremental pressure-correction time-stepping structure.