Modeling and Simulation of Generalized Newtonian and Viscoelastic Fluid Flows in Screw Turning Extruder in the Presence of Leakage Flow Using OpenFOAM Software

This manuscript presents a simulation of viscoelastic and generalized Newtonian fluid flows in a single screw extruder (SSE) considering that the extruder screw is turning instead of its barrel, which normally was considered in most simulations as an assumption. A three dimensional finite-volume scheme is used to solve momentum and the fluid constitutive equations. The really geometrical mesh of the channel is generated to investigate pressure, velocity, shear stress, and normal stress changes. The simulation is done considering the condition of existence and absence of leakage flow, and results are compared. The simulations concern incompressible flow of the Carreau–Yasuda generalized Newtonian and Phan–Thien/Tanner (PTT) viscoelastic fluids. The obtained results are shown in contour and vector form based on special position onto the axial flow. Numerical results demonstrate the influence of boundary conditions (fixed and mobile barrel assumption and omitted leakage assumption) and rheological properties on the flow characteristics in considered geometry. The results show that screw moving as realistic conditions instead of the mobile barrel assumption in single extruder have significant effects on pressure, stress, and velocity profiles comparing to results obtained from simulation with the assumption of fixed barrel boundary that currently is used to model extruder flows. Presented results show that the pressure profile and flow fields change upon changing the assumption of the static boundary. The simulations also predict the different pressure profile and flow characteristics for the generalized Newtonian and viscoelastic fluids.

Keywords:

Single screw extruder , realistic geometry , Carreau–Yasuda model , PTT model , leakage boundary effects