Numerical Simulation of Self-sustained Oscillations of an Airfoil at a Transitional Reynolds Number Using High Order Schemes
Bibliographic record
Abstract
This paper is to investigate self-sustained oscillations of a NACA 0012 airfoil at a transitional Reynolds number using large-eddy simulation (LES). The unsteady compressible Navier-Stokes equations coupled with the Smagorinsky sub-grid scale (SGS) model are solved using a dual time stepping method. The unfactored line Gauss-Seidel relaxation iteration is employed for time marching. The physical temporal terms are discretized using a 2nd-order accuracy backward differencing scheme. To achieve high accuracy, a 5th-order weighted essentially non-oscillatory (WENO) scheme is used for the inviscid fluxes. The viscous terms are discretized using a fully conservative 4th-order or 2nd-order central differencing scheme. A preconditioning method is used for the unsteady computations of the static airfoil at the beginning to generate a good initial solution for the fluid-structural interaction (FSI) computations. A fully coupled fluid-structural methodology is employed. The structurally linear one-degree-of-freedom equation of pitching motion is solved according to the low-amplitude self-sustained oscillations observed in the experiment. All simulations are conducted on a message-passing interface (MPI)-based computer cluster with parallel computations to reduce the wall clock time. The preliminary two-dimensional (2D) LES results show that the developed computational fluid dynamics (CFD)/computational structure dynamics (CSD) simulation is able to capture the self-sustained oscillations with small amplitudes observed in the experiment. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".