关键词: 分步算法, 挤出胀大, 有限元法, 粘弹性流

Abstract: With the introduction of the finite incremental calculus procedure a pressure stabilized mass conservation equation is reconstructed to overcome spurious oscillations of resulting pressure spatial distribution due to incompressibility of fluids. The discrete elastic viscous stress splitting method is used to retain an elliptic contribution in the weak form of the momentum equation in the absence of a purely viscous contribution or as the viscous contribution is negligible in comparison with the viscoelastic contribution. Inconsistent streamline upwinding method is employed to spatially discretize the constitutive equation of the Phan-Thien-Tanner viscoelastic constitutive model. The mass, momentum and constitutive equations are discretized and solved by the iterative stabilized fractional step algorithm based on Crank-Nicolson implicit difference scheme. The moving free surface is captured and determined in terms of the stream function. The isothermal extrusion swelling simulations for low density polyethylene and linear low density polyethylene melts are investigated. Numerical results demonstrate good agreement of numerical results obtained by the proposed algorithm with those given in the literature and experiment results.

Key words: Fractional step algorithm, Extrusion swelling, Finite element method, Viscoelastic flow