Tracking of immiscible interfaces in multiple-material mixing processes

A numerical study is presented for tracking immiscible interfaces with piecewise linear (PLIC) volume-of-fluid (VOF) methods on Eulerian grids in two and three-dimensional multiple-material processes. The method is coupled with the continuum surface force (CSF) algorithm for surface force modelling, supported by a multi-grid solver that enabled the resolution of large density ratio between the fluids and fine scale flow phenomena. A numerical modelling coupled with experimental data is established and evaluated through various immiscible flow cases for maintaining sharper interfaces between multiple fluids in the meso-/micro-scale, including the test symbol falling, collapsing cylinder of water, and a viscous drop deformation. The immiscible binary metallurgical flow in a shear-induced mixing process is investigated to study the fundamental mechanism of the twin-screw extruder (TSE) rheomixing process. It is observed that the rupturing, interaction and dispersion of droplets are strongly influenced by shearing forces, viscosity ratio, turbulence, and shearing time. Preliminary results show a good qualitative agreement with experimental results of a rheomixing process.