Direct simulations of orientational dispersion of platelet particles in a viscoelastic fluid subjected to a partial drag flow for effective coloring of polymers

Abstract

In this study, we performed three dimensional viscoelastic flow simulations with freely suspended platelet particles for the application of effective coloring of polymers. The model problem with a partial drag surface mimics a recently proposed design to remove typical platelet particle orientation near the weld line. A standard combination for the particulate viscoelastic flow simulation techniques is employed: (i) the discrete viscous elastic stress splitting (DEVSS) scheme for the stable solution of the viscoelastic flow; (ii) the discontinuous Galerkin (DG) method to deal with the convection term in the viscoelastic stress evolution equation; (iii) a fictitious domain method (the rigid-shell description) for implicit treatment of the hydrodynamic interaction between particles and fluid. Through example problems with a single, two and many platelet particles, we report that the angular rotation of platelet particles is significantly reduced in a viscoelastic (Giesekus) fluid compared with that in a Newtonian fluid and that non-uniform angular rotation of particles can be generated by the spatial distribution of particles, which facilitates enhanced orientational dispersion by randomizing the platelet particle orientation.