Computer Flow Simulation of Moffatt Eddies in Single Screw Extrusion
Bibliographic record
Abstract
Abstract A 3D flow analysis package is used to simulate the flow phenomena in a short section of the metering zone of a single screw extruder. The assumption of stationary screw and rotating barrel is used. For sharp flight root corners, in addition to the primary flow field a secondary flow was determined in front of the root of the pushing flight and behind the root of the trailing flight, akin to what is known in the fluid mechanics literature as Moffatt eddies. Fluid particles caught in Moffatt eddy regions require travel times which are at least two orders of magnitude larger than the average residence time. This implies high probability of degradation and explains the deposits of thin carbonaceous films and gels, which have been discussed in several publications in the technical literature. The computer simulations show the existence of Moffatt eddies in the presence or absence of pressure gradients. When the screw roots have relatively wide angles no Moffatt eddies are predicted, in agreement with recommendations for good screw design practices.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".