Bibliographic record
Abstract
A series of laboratory experiments was conducted to study the dynamics of sand–water coaxial jets in stagnant water. The effects of the velocity ratio of the annular to the core jets on the sand concentration, velocity, mixing properties, and energy distribution of sand–water coaxial jets were studied. In comparison to sand jets, the existence of carrier fluid in sand–water coaxial jets decreased the concentration fluctuations of sand particles. Proper orthogonal decomposition (POD) and spectral proper orthogonal decomposition (SPOD) techniques were utilized to study the low-rank dynamic behavior on flow entrainment and particle oscillations. It was indicated that the first two POD modes have the most coherent and energetic quantitative flow features during the entrainment process. The energy contribution of the first five POD modes was reduced by 50% in sand–water coaxial jets with relatively low velocity ratios of Ru<0.35. The SPOD analysis revealed that particle oscillations can be characterized by the Kelvin–Helmholtz type wave instabilities, and sand–water coaxial jets with small velocity ratios (i.e., Ru<1.24) had weaker vortex shedding and particle velocity fluctuations. The SPOD analysis indicated that most of the turbulence kinetic energy was concentrated in the low-frequency modes and coaxial jets with high-velocity ratios. The power spectral density (PSD) of concentration signals demonstrated that the dominant frequency of vortex shedding increased by increasing the radial distance from the jet axis. The PSD analysis of sand concentration for Ru=0.62 and 0.74 was consistent with the Kolmogorov scaling law at dominant frequencies ranging between 30 and 40 Hz.
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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 | 0.000 |
| 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 | 0.000 |
| 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".