Direct numerical simulation of turbulent flow over wide‐rib rectangular grooves
Bibliographic record
Abstract
The turbulent flow over the wide‐rib rectangular grooves, the motions and variations of near‐wall streamwise vortices with time, and the interaction between microgroove and near‐wall streamwise vortices were investigated by direct numerical simulation method (DNS). The distributions of radius, density, and swirling strength of streamwise vortex were also studied quantitatively by using swirling‐strength criterion. It was found that the distribution of vortex radius in smooth channels can approximately be divided into three parts. The vortex radii are smaller in grooved channels than in smooth channels and almost the same when y+ > 40 for all grooved cases. Moreover, a simple prediction method was proposed to estimate the optimal height and spacing of drag‐reducing microgrooves for different fluids, and they were about 10 and 17 wall units for water, respectively. Furthermore, using the same frictional velocity uτ to normalize the shear stress is more suitable for the quantitative comparison and analysis of different longitudinal microgrooves. The drag‐reducing mechanism of longitudinal microgrooves could be considered as the competition results between the “restriction or blockage effect” of microgroove on the near‐wall vortices (causing a drag‐reducing effect) and the “tip effect” of microgrooves caused by the scouring of higher speed fluid near the groove tip (causing a drag‐increasing effect). A large number of small streamwise secondary vortices with small swirling strength within the groove valley, which are induced by microgrooves, may be the essential reason of drag reduction by microgrooves.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".