Impact of Porosity and Permeability on Airflow and Temperature Distribution in Tunnel-Ventilated Poultry Houses: A CFD Study
Bibliographic record
Abstract
This study presents a two-dimensional (2-D) computational fluid dynamics (CFD) analysis of airflow and temperature distribution in a mechanically ventilated poultry barn, with the objective of evaluating tunnel ventilation performance and examining the role of porous media in representing caged-hen zones.Simulations were conducted in ANSYS Fluent under steady-state conditions, where porous regions were assigned realistic porosity and permeability values to account for airflow resistance in bird-occupied sections.Results show that permeability is the dominant factor influencing barn microclimate, with variations causing temperature differences of more than 10 °C, while porosity plays a secondary role, reducing maximum temperature by up to 6 °C as values increase from 0.5 to 0.9.Although porosity contributed modestly to heat dissipation, airflow largely bypassed the porous zones and circulated near the ceiling, limiting its effect on ventilation efficiency.A key finding is the uneven temperature distribution across the barn: localized hot spots were observed near the inlet area, while birds near the fans experienced cooler and more comfortable conditions.Such nonuniformity can compromise bird welfare and productivity, highlighting the importance of design modifications to improve airflow distribution.The use of flow deflectors is suggested as a practical solution to direct airflow into caged zones, enhance cooling efficiency, and reduce thermal gradients.The study also highlights the limitations of 2-D modeling, which cannot fully capture complex three-dimensional flow circulation, especially around cage arrays and ventilation inlets.Future work should therefore employ 3-D simulations to explore the combined effects of porous media properties, deflector placement, and inlet flap angles on airflow uniformity and thermal regulation.Overall, the findings emphasize the necessity of accurately characterizing porous media, particularly permeability, and call for empirical measurements of livestock flow resistance to enable realistic simulations and support the design of optimized ventilation systems that ensure bird health and welfare.
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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 | 0.000 | 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".