Modeling Flow over a Circular Cylinder with a Stepwise Discontinuity
Bibliographic record
Abstract
Flow past a circular cylinder with a single stepwise discontinuity was investigated using an unsteady RANS based numerical approach for ReD = 300. The primary focus was on the vortex shedding phenomena occurring in the wake of a step cylinder. Based on the numerical results, three distinct spanwise vortex cells were identified in the step cylinder wake. A comparative analysis with available experimental data showed that the numerical simulations adequately modeled not only wake vortex development but also interactions between the identified vortex cells in the near wake region. One of the vortex cells, forming in the vortex interaction region downstream of the step, was found to have a quasi-periodic appearance, with the periodicity being linked to downwash fluctuations near the step. In addition to spanwise wake vortices, the results suggest that streamwise vortices develop at the step, and that unsteady interactions between the streamwise and spanwise vortices occur. Nomenclature CD = drag coefficient, FD/(0.5ρLDU2) CD,L = local drag coefficient for the large cylinder CD,S = local drag coefficient for the small cylinder D = large cylinder diameter d = small cylinder diameter FD = drag force in x direction f = vortex shedding frequency fL = vortex shedding frequency of the L-Cell fN = vortex shedding frequency of the N-Cell fS = vortex shedding frequency of the S-Cell L = span of the cylinder NC = number of spanwise cells in a region of 1D surrounding the step ReD = Reynolds number, UD/ν St = Strouhal number, fD/U T = period of the N-Cell cycle U = free-stream velocity in x direction u, v, w = streamwise, transverse, and spanwise velocity components X, Y, Z = streamwise, transverse, and spanwise coordinates ρ = density ν = kinematic viscosity I.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".