Detecting mixing barriers in Twin-Screw extruder elements via Lagrangian Coherent Structures

Hannes Bauer, Johannes Khinast*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Twin-screw extruders (TSEs) are known for their good mixing performance. Although global mixing performance has been the subject of many computational fluid dynamics studies, the actual mixing mechanism remains largely unexplored, probably due to the complexity of chaotic flow patterns caused by the complex screw geometry. In this work, we aim to understand laminar mixing in various twin-screw extruder elements via Lagrangian Coherent Structures (LCS). An LCS computation requires fluid element trajectories, which can be a limiting factor in 3D applications. Bypassing this potential problem, we evaluated LCS within a Smoothed Particle Hydrodynamics (SPH) framework and established that, unlike conventional methods, this methodology is efficient in complexly shaped deforming fluid domains. Mixing barriers in realistic conveying, kneading and mixing elements are computed, compared, and discussed. Repelling and attracting LCS reveal the stretching and folding events necessary for efficient laminar mixing and offer a novel viewpoint for geometry optimization.

Original languageEnglish
Article number118069
JournalChemical Engineering Science
Publication statusPublished - 14 Dec 2022


  • Lagrangian Coherent Structures
  • Laminar mixing
  • LCS
  • Smoothed particle hydrodynamics
  • SPH
  • TSE
  • Twin-screw extruder element

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering


Dive into the research topics of 'Detecting mixing barriers in Twin-Screw extruder elements via Lagrangian Coherent Structures'. Together they form a unique fingerprint.

Cite this