Multiphase flows and mixing in partially filled conveying elements of twin-screw extruders (TSEs) were simulated by using smoothed-particle hydrodynamics (SPH). A validation of SPH using experiment from the literature for a co-rotating twin-cam mixer indicated good agreement. A two-phase Poiseuille flow was also used to validate the accuracy of our approach. The results of two-phase flow in TSE show that the viscosity ratio significantly affects the flow and mixing of two-phase fluids. The symmetry of flow field is broken with different parameters. In the full filled case, the pressure squeezes particles into the gap, which is conducive to improve the performance of mixing of fluids. On the contrary, in the partially filled case, because there is no background pressure, particles tend to bypass the gap and flow to the cavity of the chamber. This work laid a foundation for further study of polymer blending by simulation.

Vibration-assisted methods are playing a more and more important role in processing polymers for twin screw extruders (TSEs) in order to satisfy the increasing requirements for polymetric products in various applications, but existing vibrating technologies are usually restricted in school laboratories and industrial research rooms because of their drawbacks. The purpose of this study is to design a novel vibration method for TSEs. Numerical simulation was performed based on a meshless method, namely smoothed particle hydrodynamics (SPH). The velocity distribution, particle distribution, and pressure of particles in a co-rotating twin screw component in the conveying zone of a TSE are investigated in detail to recover the influence of the rotational speed excitation on the flow properties of both fully filled and partially filled states. The results show that cases under superimposed excitation can produce a more variable physical effect, thus enhancing and weakening the velocity field and the pressure field alternately. And on the whole, that effect could improve the particle distribution in according cases. These findings can lay a solid foundation for further study on the development and application of superimposed excitation technology in the polymer processing of TSEs.

Vibration-assisted technology has been employed to satisfy various requirements for different polymeric products due to its excellent performance, but because of the large inertia of the vibration excitation system, these attempts are strictly limited to several fixed vibration amplitudes and frequencies in small extruders or injectors. The purpose of this study is to carry out a numerical investigation via smoothed particle hydrodynamics (SPH) and to perform a comparative analysis of physical parameters among different cases from various perspectives on the fluid channel in twin-screw extruders (TSEs). The results demonstrate that certain combinations of larger vibration amplitudes and frequencies can significantly enhance the velocity, pressure, and particle distribution characteristics within the flow channel. However, no monotonic (i.e., strictly increasing or decreasing) trends are observed with respect to either amplitude or frequency alone. These findings are in excellent agreement with previously reported experimental studies and confirm that the meshless smoothed particle hydrodynamics (SPH) method is a robust and effective computational tool for investigating how various vibrational parameters influence flow behavior in twin-screw extruders (TSEs). Moreover, the results underscore that optimal amplitude and frequency selections must be tailored to the specific rheological and thermal properties of the polymer being processed. This work establishes a solid theoretical and numerical foundation for integrating superimposed vibration-assisted technology into the design optimization of TSE systems.