A novel measurement method for mixing in smoothed particle hydrodynamics simulation of multiphase flow in a twin screw extruder

A novel method for measuring mixing is proposed and applied to the smoothed particle hydrodynamics (SPH) simulation of multiphase flows in a co‐rotating twin screw extruder. The core principle utilizes the inherent SPH particle identification number (ID) to define the local mixing index of particles based on the weighted average of their ID differences from adjacent particles. A two‐dimensional SPH simulation of a droplet dispersing in a continuous phase is demonstrated, and the results agree well with those of a purpose‐built visual experiment. Simulations reveal the deformation and breakup dynamics of droplets at different initial locations (near the screw, cavity center, and barrel). The proposed mixing measurement method can not only measure distributive mixing of the continuous phase but also capture the key events in dispersing mixing of droplets, such as droplet breakup and coalescence. It offers a robust tool for analyzing mixing processes for particle‐based simulations.