Buoyant plumes with inertial and chemical reaction-driven forcing
Notice bibliographique
Résumé
Plumes are formed when a continuous buoyant forcing is supplied at a localized source. Buoyancy can be created by either a heat flux, a compositional difference between the fluid coming from the source and its surroundings, or a combination of both. In this thesis, two types of laminar plumes with different forcing mechanisms were investigated: forced plumes and autocatalytic plumes. The forced plumes were compositionally buoyant and were injected with inertial forcing into a fluid filled tank. The autocatalytic plumes were produced without mechanical forcing by buoyancy that was entirely the consequence of a nonlinear chemical reaction -- the iodate-arsenous acid (IAA) reaction. This reaction propagates as a reacting front and produces buoyancy by its exothermicity, and by the compositional difference between the reactant and product. Both the forced and autocatalytic plumes were examined in starting and steady states. The starting, or transient, state of the plume occurs when it initially rises through a fluid and develops a plume head on top of a trailing conduit. The steady state emerges after the plume head has risen to the top of a fluid filled tank leaving only a persistent conduit. Plume behaviour was studied through experimentation, simulation, and by using simple theoretical analysis. We performed the first ever study of plumes as they crossed over the transition between buoyancy-driven to momentum-driven flow. Regardless of the driving mechanism, forced plumes were found to exhibit a single power law relationship that explains their ascent velocity. However, the morphology of the plume heads was found to depend on the dominating driving mechanism. Confined heads were produced by buoyancy-driven plumes, and dispersed heads by momentum-driven plumes. Autocatalytic plumes were found to have rich dynamics that are a consequence of the interplay between fluid flow and chemical reaction. These plumes produced accelerating heads that detached from the conduit, forming free vortex rings. A second-generation head would then develop at the point of detachment. The detachment process for plumes was sensitively dependent on small fluctuations in their initial formation. In some cases, head detachment could occur multiple times for a single experimental run, thereby producing several generations of autocatalytic vortex rings. Head detachment was reproduced and studied using autocatalytic plume simulations. Autocatalytic flame balls, a phenomenon closely related to autocatalytic plumes, were also simulated. Flame balls were found to have three dynamical regimes. Below a critical radius, the smallest flame balls experienced front death. Above this radius, they formed elongating, reacting tails. The largest flame balls formed filamentary tails unable to sustain a reaction.
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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) | 0,000 | 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 ».