Analysis of dynamic flows through porous media. Part II: Deformation of a double‐scale fibrous reinforcement
Bibliographic record
Abstract
Abstract Porous media are encountered in numerous applications from Soil Mechanics to composite materials manufacturing. Part I of this article investigated the flow behavior in a double‐scale porous medium, i.e., in a material with a bimodal distribution of pore sizes. Typical examples of such medium are the dry fibrous reinforcements used in composite manufacturing through which resin is injected. This type of porous medium contains two types of pores: microscopic voids inside the fiber tows and macroscopic ones between the tows. Because of this double‐scale structure, the saturation of such reinforcing materials is not instantaneous during resin injection. Part I has shown that the notion of saturation must be taken into account in order to describe accurately transient unsaturated flows during the filling of double‐scale fibrous materials. Part II of this investigation is concerned with the transient flow behaviors that can be observed once the reinforcement is saturated. In permanent regime, saturated resin flows are governed by Darcy's law, which describes the purely linear pressure drop observed in fully saturated reinforcements. However, this model cannot be applied to transient saturated flows unless they are considered as a succession of quasi‐stationary flows. Simple macroscopic measurements during transient flow regimes permit us to derive important information on the microscopic characteristics of the flow in connection with the deformations of the porous medium under the effect of fluid pressure. The pressure variations in time observed in permanent flow regimes, when the flow rate is changed, are connected with the double‐scale porosity structure of the fibrous reinforcement. Therefore the second part of this analysis is focused on the stress‐stain behavior of fibrous reinforcements deformed by the pore pressure. A physical model based on Kelvin‐Voigt visco‐elastic material is proposed here to describe the dynamic compaction and relaxation behaviors of saturated fibrous reinforcements. This approach is not only in good agreement with experiments, but it shows also that double‐scale effects are intimately connected with the pressure variations observed in transient saturated flows.
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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) | 0.000 | 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".