Nonlinear spin-up flow in magnetic colloidal suspensions under high-frequency rotating magnetic fields
Bibliographic record
Abstract
We investigate the spin-up flow dynamics of dilute ferrofluids under a rotating magnetic field with a focus on high frequencies. Three models are compared: the first- and second-order approximations of the orientational probability density function and the full Smoluchowski equation. The first-order approximation, while computationally simple, has not been tested for its validity in high-frequency regimes, nor has it been compared with experimental data in such regimes. A parametric study explores the effects of magnetic field intensity, nanoparticle concentration, and particle diameter in the clusterless regime. Two types of ferrofluids—water-based and oil-based—are considered, each with different behaviors at high frequencies. The results show a transition in spin-up behavior from increasing torque and velocity with frequency to a regime where torque flattening causes flow attenuation. While the full Smoluchowski model captures additional nonlinear effects, the second-order approximation offers a computationally efficient and accurate alternative. It provides a good balance between accuracy and efficiency, especially when additional phenomena, such as the Kelvin body force, come into play.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".