Viscoelastic flow in a periodically constricted tube: The combined effect of inertia, shear thinning, and elasticity

Abstract

The flow of a shear‐thinning viscoelastic fluid (Separan AP‐30) through a periodically constricted tube (PCT) is simulated using a mixed pseudospectral finite difference numerical method and a variety of constitutive equations. The results obtained with viscoelastic models show, at best, a small increase in the flow resistance beyond the value computed for a purely viscous inelastic fluid. The largest increase was observed with the modified Phan‐Thien–Tanner model. This model, in addition to fitting the standard viscometric data (viscosity and first normal stress difference), predicts a nonzero second normal stress difference and allows for dynamic behavior characterized by nonaffine deformation and stress overshoot in start‐up of shear flow. All the calculated values, although they show the correct tendency, are well below the experimentally measured values of Deiber and Schowalter (1981).