Simulation Double Screw Extruder with Kneading-Block

Figure 1: CAD model created in NOGRID's COMPASS

Figure 2: Setup the extruder case within the GUI

Figure 3: Extruding state at a certain time step

Figure 4: Short animation of the extrusion process

The simulation of double screw extruders with a kneading-block can perfectly be performed with our CFD software NOGRID points. Double screw extruders (twin-screw extruders) belong to the group of multi-screw extruders and are machines that are used in plastics technology for processing thermoplastics. In plastics technology, they are used for the preparation and extrusion of plastic melts. In the extruder, the polymer to be processed is fed lengthwise through a heatable cylinder by means of two rotating screw shafts. The material is melted in the process.

In this study we do not compute the feeding and melting zone but focus on the compression zone and mixing zone. Due to the given mass flow rate of the extruder and the conveying effect of the screws, the material is compressed. This increases the pressure and the shear rate and the material starts to melt. Special mixing or kneading elements can be integrated into the screw. This increases the mixing performance. This is particularly important when a homogeneous incorporation of aggregates is required.

NOGRID unites abilities to handle free surface flow and moving parts in the domain and allows the simulation of any conceivable geometry and operation modes such as

  • computation is in full 3D solving complete Navier-Stokes-Equations
  • easy and intuitive setup of the FSI (Fluid-Structure-Interaction) case
  • free definable PUR material properties by equations or curves
  • polyurethane (PUR) injection by one or more inlets
  • open or closed domains including moving of additional parts
  • moving of the mixing head

Nogrid's strengths

Particular strengths of NOGRID's fluid flow CFD software 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.
Easy Modelling

Easy and fast modelling: Build geometry, mesh boundary, setup the case and start computation

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 for flow modeling 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.




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:




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.

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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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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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