Simulation Single Screw Extruder

With the simulation of a single screw extruder the meshless CFD software NOGRID points provides valuable insights into the internal flow behavior. Simulating screw extruders is crucial for optimizing extrusion effiiciency and ensuring consistent product quality. NOGRID software delivers accurate simulations for a wide range of extruder designs.
In this example, a barrel with a constant radius is shown, featuring an inflow area at the top. A Newtonian fluid with a viscosity of 1 Pas is injected at the inlet, gradually filling the extruder over time.

Functions of screw extruders

In this example, we solve the complete Navier-Stokes equations, including temperature transport.  Screw extruders, commonly used in the healthcare and food industries, represent a highly important class of pumps for processing non-Newtonian materials. Depending on the application, one key function of the screw pump is to transport fluid while minimizing shear in the channel between the screw and the barrel wall.

Implemented models in NOGRID points

In this case study, the single screw extruder is initially empty and gradually filled with fluid over time. This example also demonstrates the free surface capabilities of the NOGRID fluid simulation software, as it allows for the simulation of partially filled extruders. While the viscosity of the fluid is constant in this simple case, the NOGRID points CFD software includes a wide range of non-Newtonian material models for more advanced simulations: 

• Bird-Carreau-Yasuda with and without WLF shift:
  The Bird-Carreau_Yasuda model is a general model for capturing strain-rate dependent viscosities in polymer rheology. At small strain rates, it behaves like a Newtonian fluid with (almost) constant viscosity. For very large strain rates, it resembles the power law. The Williams-Landau-Ferry model adds a temperature dependent shift factor.
• Carreau with and without WLF shift
• Cross with and without WLF shift
• Menges-Wortberg-Michaeli
• Power law
• Bingham-Herschel-Bulkley-Papanastasious

Features of NOGRID points software

The CFD software NOGRID points  provides valuable insights into the flow behavior within a partially filled single screw extruder. The screw (or auger) serves to reduce friction and support cooling, with the effectiveness of cooling depending on the screw size and the fluid transport rate.  NOGRID CFD software combines the capability to simulate free surface flows and moving parts within the computational domain, enabling the simulation of any screw geometry and operating mode, such as: 

• computation is in full 3D solving complete Navier-Stokes-Equations
• easy and intuitive setup also for partially filled extruders
• free definable material properties by equations or curves
• injection by one or more inlets
• open or closed domains including moving of additional parts
• moving and rotating of the screws