Deflection of a dilute stream of particles
Bibliographic record
Abstract
We consider a two-dimensional system in which a dilute stream of particles collides with an oblique planar wall. Both collisions between particles and collisions between particles and the wall are inelastic. We perform numerical simulations in two dimensions and show that the mean force experienced by the wall can be a nonmonotonic function of the angle between the wall and the particle stream. We show that this occurs because particles that rebound from the wall can collide with incoming particles and be scattered. This kind of particle-particle collision can reduce the force experienced by the wall. We refer to this effect as shielding. Furthermore, we show that the force experienced by the wall may be an increasing, decreasing or nonmonotonic function of the restitution coefficient in particle-particle collisions. We derive an exact solution for the mean force on the wall if the system is dilute, and the theoretical prediction is found to be in good agreement with our numerical results. The theory allows us to explicitly quantify the effects of shielding, and thus to explain a number of interesting features. The theory generally provides a useful upper bound for the mean force.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| 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".