| # NASA ASJ — Axisymmetric Subsonic Jet |
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| Validation case from the **NASA TMR Collaborative Testing Challenge 2022** ([turb-prs2022](https://tmbwg.github.io/turbmodels/turb-prs2022.html)). Acoustic reference Mach M_jet ≈ 0.5. |
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| ## Required metrics |
| 1. **u/U_jet vs. x/D_jet** — centerline velocity decay |
| 2. **u/U_jet vs. y/D_jet at 5 specified stations** — radial velocity profiles |
| 3. **u'v'/U_jet² vs. y/D_jet at 5 specified stations** — Reynolds-stress profiles |
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| Compared with the Bridges & Wernet ARN (Acoustic Reference Nozzle) consensus PIV dataset. |
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| ## Folder layout |
| ``` |
| NASA_ASJ/ |
| ├── baseline_komegasst/ k-ω SST integral profiles (.dat + .csv) |
| ├── highfidelity/ ARN PIV experiment + NASA WIND SSTV CFD reference |
| └── plots/ Pre-rendered comparison figures + plot_profiles.py |
| ``` |
| |
| The full transient OpenFOAM case (mesh, time-averaged fields, post-processing) is hosted separately on the heavy CFD-asset Hugging Face dataset linked in the paper. |
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| ## Solver / setup |
| - **Solver**: `rhoPimpleFoam` (compressible transient, with `fieldAverage` to produce mean fields) |
| - **Turbulence model**: `kOmegaSST` (baseline, no augmentation) |
| - **Time-averaging window**: last half of run, captured in `*Mean` fields |
| - **Mach**: M_jet = 0.5 |
| - **Why transient**: the jet shear layer is convectively unstable; a steady SIMPLE iteration does not converge cleanly. Time-stepping with field averaging is the equivalent of a converged steady RANS solution here. |
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| ## Submission format |
| Three files matching the columns of the bundled baseline: |
| - `ASJ_u_vs_x.csv` — `zone`, `x/Dj`, `u/Uj` (single zone, centerline) |
| - `ASJ_u_at5stations.csv` — `zone`, `u/Uj`, `y/Dj` (one zone per station: `x/Djet=2`, `5`, `10`, `15`, `20`) |
| - `ASJ_uv_at5stations.csv` — `zone`, `u'v'/Uj^2`, `y/Dj` (same zone structure) |
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| Then `python plots/plot_profiles.py` overlays the baseline + reference + your model. |
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