Mixing and extrusion processes Analysis and Optimization

Source : Cemef, from the CIMLIB by Thierry COUPEZ and Guillaume FRANCOIS

The Free Surface Modeling allows to take into account an area which is not totally full of material.

In this case, a continuous mixer is represented (it is being filled). The used product is very viscous (low Reynolds number) which explains is elastic behavior.

A feeding zone is represented by the green arrow, the exit zone by a red one.

The Splash Pheonomenon illustrates the Cimlib efficiency for turbulent and high Reynolds fluids. These first Research results performed at the CEMEF will be soon adapted in XimeX.

XimeX is a modeling program aimed at the analysis of the material flow during the process, taking into account all process components.

XimeX reproduces all kind of equipments used for the mixing and transformation of materials : from the most classical one (Single screw, twin screw, batch, static or planetary mixer, Buss kneader...) to the most specific one (realised on demand).

Using a unique innovative technology, XimeX provides two kind of analysis :

• A global analysis of the studied process : computation of the process trends, geometry, operating conditions and material impact on the product quality...
• A local analysis : to underline a special element or behaviour while taking into account the process global behaviour.

Particles dissemination in a twin screw

A thermo mechanical analysis
Navier-Stokes / Stokes :

• Shear rate
• Pressure
• Speed fields
• Filling rate
• Temperature
• Residence Time Distribution
• Elongation Computations
• ...

Flow in a batch mixer

Pressure field modelling in a single screw

An innovative Technology :

• Adaptative and automatic meshing for an immediate handhover
• Parallelised computations and post-process for more fastness
• Material and elements libraries for a regular use
• Import/Export of simulation and modelling parts to carry the innovation

Adaptative meshing on a single screw case

Many physical and numerical models included in XimeX consider the most complex physical phenomena stepping in mixing and extrusion processes :

• Fluids Mechanical
  • Gravity
  • Free Surface
  • Sliding
• Thermal model
• Particles
  • Distributive/Dispersive Mixing
  • Lyapunov coefficient
  • Particles properties evolution (size, shape...)

Flow modelling in a batch mixer with free surface