writer：Wang Wei, Hu Changxu, Li Wenwen
keywords：Numerical simulation, Complex flow, Rheological behavior, Extensional flow; Viscoelastic constitutive models; Polymer melts
source：期刊
specific source：Mechanics of Time-Dependent Materials
Issue time：2016年

The viscoelastic flow of low-density polyethylene melts in a cross-slot channel is studied numerically for the double convected Pom–Pom (DCPP) and single modified DCPP (S–MDCPP) models. The equal low-order finite elements for velocity–pressure–stress variables are implemented to solve the flow fields using the pressure-stabilized iterative fractional step algorithm. The distributions of axial velocity along the channel centerline and the principal stress difference achieved by numerical predictions are in quantitative good agreement with the reported experimental results. Furthermore, the evolution of backbone stretch of macromolecule with flow time is demonstrated, and then we propose an exponential decay function linking the microscale stretch relaxation time with the macroscale flow time, in order to reveal the stretch relaxation response of the branched polymer. The effects of the Weissenberg number and several constitutive parameters of the S–MDCPP model on the rheological behavior of polymer melts are discussed.

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