Molecular Modeling of Viscoelastic Flow with Free Surface

Abstract

Viscoelastic flow simulation is a difficult work when one faces the complicated constitutive equation. A possible way to avoid this is to use the Brownian dynamics method — CONNFFESSIT, which has already been proved to be successful in many applications. By using this method, one should replace the constitutive equation with the so‐called “Brownian Configuration Field” (BCF) equation and use the statistical method to calculate the stresses coming from the contribution of the polymer molecules. Transient free surface simulation in the viscoelastic flow is challenging because we need to calculate the velocity field and track the moving free surface at the same time. In this presentation, the modified DEVSS‐G/SUPG method associated with the ALE method is used for the die‐exit flow and the long bubble penetration flow using the CONNFFESSIT approach. The spine method is used to track the movement of the free surface. We study two bead‐spring dumbbell models: the Hookean and FENE dumbbells. A Gaussian random generator is used to simulate the stochastic process — the standard Wiener’s process. Results are also compared with those using the Non‐Newtonian Oldroyd‐B constitutive model.