CFD model estimates of the airflow distortion over research ships and the impact on momentum flux measurements
Notice bibliographique
Résumé
Wind velocity and air–sea turbulent flux measurements made from shipborne instruments are biased due to the effect of the ship on the flow of air to the instruments. The presence of the ship causes the airflow to a particular instrument site to be either accelerated or decelerated, displaced vertically, and sometimes deflected slightly in the horizontal. Although recognized for some time, it is only recently that the problem has been addressed using three-dimensional computational fluid dynamics (CFD) models to simulate the flow over particular ships, quantify the effects of flow distortion, and hence correct the ship-based measurements. It has previously been shown that this improves the calculated momentum fluxes by removing disparities between data from different ships, or from instruments in different locations on the same ship. \n \nThis paper provides validation of the CFD model simulations. Two research ships were instrumented with multiple anemometers located in both well-exposed and badly exposed sites. Data are compared to the results of model simulations of the flow at various relative wind directions and wind speeds. Except when the anemometers are in the wake of an upwind obstruction, the model and the in situ wind speed estimates typically agree to within 2%. \n \nDirect validation of the model-derived estimates of the vertical displacement of the flow was not possible due to the extreme difficulty of obtaining such measurements in the field. In this study, simulations of flows at 0° and 90° from the bow of the ship were made and displacements of about 1 and 5 m were found, respectively. These results were used to correct the in situ momentum flux data. In one case, the application of the different bow-on and beam-on corrections for vertical displacement successfully removed the disparity seen in the uncorrected data. In a second case, the beam-on vertical displacement overcorrected the flux results. This overcorrection could be caused either by uncertainties in the in situ estimate of the relative wind direction or by partial adjustment of the turbulence during the vertical displacement. \n \nThe effects of flow distortion are found to vary only slightly with wind speed, but are very sensitive to the relative wind direction and, if uncorrected, can cause large biases in ship-based meteorological measurements (up to 60% for the drag coefficient). Model results are given for bow-on flows over 11 research ships (American, British, Canadian, French, and German).
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,005 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».