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).