Numerical Investigation of Dynamic Stall on a NACA 4412 Airfoil under Harmonic Pitching using URANS
Bibliographic record
Abstract
This study presents a numerical investigation of dynamic stall phenomena on a NACA 4412 airfoil undergoing harmonic pitching motion, using an unsteady Reynolds-averaged Navier-Stokes (URANS) approach with the Shear Stress Transport (SST) k- turbulence model.The primary objective is to quantify transient lift, drag, and pitching moment coefficients as functions of reduced frequency and pitching amplitude, and to assess the capability of URANS in capturing key dynamic stall characteristics.A twodimensional C-grid mesh was generated around the NACA 4412 profile, ensuring near-wall resolution of y 1. Steady RANS solutions at Reynolds number 1 10 provide initialization, followed by transient simulations in ANSYS Fluent Student Version using a secondorder implicit time-marching scheme.Pitching motion is imposed via a dynamic-mesh user-defined function (UDF) to prescribe sinusoidal oscillations about the quarter-chord at reduced frequencies (k) of 0.05 and 0.10, and pitching amplitudes of 10.Results reveal pronounced lift overshoots and a clear hysteresis loop in the lift coefficient versus angle of attack response, with stall onset delayed by up to 20 beyond the static stall angle.Drag and moment coefficients exhibit corresponding unsteady peaks.The Strouhal numbers derived from post-stall vortex shedding agree within 5% of classical experimental values.A mesh and time-step sensitivity study confirms convergence of peak lift and hysteresis area within 3%.These findings demonstrate that URANS coupled with the SST k- model can reliably predict unsteady aerodynamic loads associated with dynamic stall, making it a viable tool for preliminary rotorcraft and windturbine airfoil design.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".