Vibrational effect on heat transfer and entropy generation in an elliptic porous cavity
Bibliographic record
Abstract
Purpose Free convection inside a square, circular, or elliptic cavity with gravity oscillation is a special class of problems. In a microgravity environment, the reduction or elimination of natural convection can enhance the properties and performances of materials such as crystals. However, aboard orbiting spacecrafts, all objects undergo low‐amplitude broadband perturbed accelerations, or g‐jitter, caused by crew's activities, orbiter maneuvers, equipment vibrations, solar drag, and other sources. Therefore, there is a growing interest in understanding the effects of these perturbations on the systems' behavior. There is no information of flow, heat transfer, and irreversibility analyses in the current literature that considers such a situation in a porous medium. This motivates this paper to conduct the current research. Design/methodology/approach As a special case, an elliptic enclosure is considered here. The enclosure is filled with a porous medium whose flow is modeled by the Darcy momentum equation. The full governing differential equations are simplified by the Boussinesq approximation and solved by a finite volume method. Prandtl number (Pr) is fixed at 1. Findings The average Nusselt number (Nu), Bejan number (Be), and entropy generation number (Ns) are adopted to characterize the heat transfer and irreversibilities. Gravity oscillation introduces periodic behavior to the Nu, Be, and Ns rate. Depending on the frequency and the Rayleigh number (Ra), three distinguishable regimes of ψ behavior are identified: periodic and synchronous, periodic and asynchronous, and non‐periodic and asynchronous. Research limitations/implications Current research is valid only for laminar Darcy type flow situation in the porous media. Originality/value This paper will extend the existing theory of thermovibrational convection to porous media.
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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 | 0.000 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".