Flow patterns in the calender gap of a counterrotating twin screw extruder

Abstract The finite element method was employed to examine the flow details in the calender gap of a counterrotating twin screw extruder. For Newtonian fluids a vortex is predicted at the entry of the calender gap. Calculations show that the vortex intensity is determined uniquely by the value of relative throughput and disappears when it exceeds 24%, for the geometrical configurations examined. Shear thinning behavior of the fluid reduces the vortex intensity. Approximate equations for the pressure drop based on the lubrication approximation are compared with the finite element results and prove accurate for engineering calculations.