1. Example: Polymer Extrusion

2. Non-Newtonian flow, Carreau viscosity
Polymer extrusion
Non-Newtonian flow, Carreau viscosity
Study the influence of shear rate dependent viscosity.
Linear polystyrene solution.
Carreau viscosity model .

3. Equations Momentum and continuity equations.
Polymer extrusion - Equations
Equations
Momentum and continuity equations.
The viscosity is dependent on the shear rate
The Carreau-viscosity is given by

4. Polymer extrusion - Geometry
Due to rotational symmetry, we can reduce the model dimensions
from 3D to axisymmetric 2D.

5. Polymer extrusion - Results
Velocity field
The average velocity is substantially lower at the outlet compared to the inlet, due to the rotational symmetry.

6. Non-Newtonian viscossity
Polymer extrusion - Results
Non-Newtonian viscossity
Large variations in the contraction between the piston and the walls of the device.
The narrow channel generates large shear rates close to the walls.