# Simulation Single Screw Extruder

Figure 1: CAD model created in NOGRID's COMPASS

Figure 2: Setup the extruder case in the GUI

Figure 3: Extruding state at a certain time step

Figure 4: Short animation of the extrusion process

With simulation of a single screw extruder the meshless CFD software NOGRID points can help to understand the flow inside. In this example we show a barrel of constant radius with an inflow area at the top of the barrel. At the inlet a Newtonian fluid with a viscosity of 1 Pas is injected and starts to fill the extruder over time.

We solve the complete Navier-Stokes equations including temperature transport in this example.  Screw extruders, as used in the health care and food industry, form a most important class of pumps for handling non-Newtonian materials. Depending on application one function of the screw pump is to transport fluid and to minimize the shear of the fluid in the channel between the screw and the wall of the barrel.

In this case study the single screw extruder is initially empty and is filled with the fluid over time. So, this example shows also the free surface capabilities of the NOGRID software as one can compute part filled extruders as well. The viscosity of the fluid is constant in this simple example, but a lot of non-Newtonian materials are implemented in the NOGRID points software:

• 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

NOGRID points can help to understand the flow in a partially filled single screw extruder. The auger is used to reduce friction and for cooling. The effectiveness of the cooling depends on the size of the screw and how fast the fluid is transported. NOGRID combines the ability to handle such free surface flows and moving parts in the definition range and allows the simulation of any conceivable srew geometry and operating modes, 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

## Nogrid's strengths

NOGRID's particular strengths are the rapid preprocessing (no fluid grid needs to be generated, only the boundary mesh, inner finite points are generated automatically depending on User setting initially and during computation) and the outstandingly short computation time even for complicated cavities.
As you can see in the image below, the boundary of the geometry still requires a mesh to allow the interior finite points to detect the boundary. The boundary must therefore be meshed and the finite points inside are automatically generated during the simulation controlled by User specifications.

## What is CFD from NOGRID?

CFD solves the fundamental equations that define the fluid flow process. With CFD software from NOGRID every engineer makes better decisions by predicting, analyzing and controlling fluid flow, heat and mass transfer or chemical reaction. By using NOGRID software you receive information on essential flow characteristics as for example flow distribution. Using it additional to testing and experimentation NOGRID software helps to improve the evaluation of your design – resulting in better construction and operation parameters, increasing planning security and money savings due to faster time to the marketplace for your product or process.

## Choose NOGRID

With NOGRID, you choose professional CFD software and services – our aim is helping you to be successful. When you decide to work with NOGRID you choose close cooperation with a dynamic, flat hierarchies-organization. Short information channels result in quick and accurate professional support and service. Our team consists of highly qualified employees, who are experts in fields such as numerical simulation or computational fluid dynamics. Based on our know-how, we are pleased to offer the following services, responding to your individual requirements:

## TRAINING

In our two-days training courses you will learn, how to use NOGRID CFD software efficiently. Our technical support team will teach you how to handle and solve different cases.

For more details please refer to Training Courses →

## Technical Support

We offer full professional support from the minute you start using our software, by telephone or by email. Contact us, when ever needed.

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## Service

Lack of time or resources and other constraints often make outsourcing an attractive solution. We help you with your flow modeling needs. Based on our engineering expertise in this field we offer individual numerical simulation services matching the unique needs of your organization.

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