Combined effects of favourable pressure gradient and streamline curvature on uniformly sheared turbulence
Bibliographic record
Abstract
The combined effects of favourable pressure gradient and streamline curvature were studied experimentally using an approximately homogeneous uniformly sheared turbulence. The shear flow was initially generated in a straight wind tunnel, where the turbulence was allowed to develop a fixed stress anisotropy, and then subsequently directed into a curved wind-tunnel test section. Streamwise pressure gradients were applied by convergence of the curved tunnel walls in the plane of the mean shear. In one set of experiments, convergence was applied in the first half of the curved test section, but not in the second half. In another set of experiments, the convergence was applied in the second half of the curved test section, but not in the first. This arrangement permitted the study of application and removal of streamwise pressure gradient to curved shear flow. Measurements showing the response of the turbulence stresses to the changing mean strain rates are reported and are consistent with previous studies which show that stabilizing curvature diminishes the turbulence energy and stresses. The addition of the streamwise strain rate associated with favourable pressure gradient was observed to have the effect of further diminishing the turbulence activity and its overall anisotropy. However, the important shear component of the anisotropy was increased above what it would be under the influence of curvature alone. The removal of streamwise strain rate caused the turbulence to recover a structure similar to that measured for uniformly curved shear flow; although this adjustment included an increase in the shear component of anisotropy prior to its gradual relaxation. The principal direction of the Reynolds stress tensor was found to be closely related to the principal direction of the mean strain rate tensor in the present flows. This result was also found to be valid in the outer layer of accelerating curved boundary layers. A relationship between the direction of the principal mean strain rate and the mean flow curvature and streamwise strain rate was formulated to explain how each influences the state of turbulence stress.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".