Numerical simulation of macroscopic viscoelastic melt filling and mesoscopic spherulite growth

In this work, a non-isothermal viscoelastic computational framework is proposed for macroscopic polymer melt filling and mesoscopic spherulite growth. Firstly, the macroscopic viscoelastic governing equation is solved by coupled level set immersed boundary and finite-volume (LS-IB-FV) method. The melt-air interface is captured by the coupled level-set and volume-of-fluid (CLSVOF) method. And the mesoscopic crystallization behavior is predicted by the phase field model. Then, the numerical simulation for melt filling process is compared with experimental one to validate the coupled method. And it is simulated that the melt filling stage in a complex annular cavity with 17 small solid discs for the semi-crystalline polymer of isotactic polystyrene, and it is studied that the impacts of three different injection velocities on the flow modes, temperature distribution and solidified layers. Finally, in the regions of solidified layers, the growth of spherulites is simulated with/without melt flows at two different points. Numerical results show that the injection velocities can affect the flow modes and temperature distribution significantly. The morphology of polymer spherulite that is consistent with the experimental result can be observed clearly. With flow fields, the spherulites grow faster and densely towards the upstream direction.