Influence of boundary conditions on computation of the effective thermal conductivity of foams
| Autor: | Zi Kang Low, Nawfal Blal, Naim Naouar, Dominique Baillis |
|---|---|
| Přispěvatelé: | Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Computation Finite elements 02 engineering and technology 01 natural sciences 010305 fluids & plasmas Thermal conductivity 0103 physical sciences [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph] Periodic boundary conditions Boundary value problem Porosity Fluid Flow and Transfer Processes Homogenization Boundary conditions Computer simulation Mechanical Engineering Mechanics 021001 nanoscience & nanotechnology Condensed Matter Physics Foam Finite element method Representative elementary volume [SPI.MECA.THER]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Thermics [physics.class-ph] 0210 nano-technology |
| Zdroj: | International Journal of Heat and Mass Transfer International Journal of Heat and Mass Transfer, Elsevier, 2020, ⟨10.1016/j.ijheatmasstransfer.2020.119781⟩ |
| ISSN: | 0017-9310 |
| Popis: | International audience; Accurate numerical simulation of the effective thermal conductivity (ETC) of 3D pore-scale foam models requires a judicious choice of boundary conditions, as the computational domains are often smaller than the representative volume element, giving rise to considerable edge effects. Within the finite element homogenization framework, a set of mixed boundary conditions are considered alongside the usual uniform and periodic boundary conditions. Validity criteria and order relations, demonstrated from entropy-based principles, are numerically verified on unit cell-based geometries, random virtual periodic foams, and non-periodic tomography-reconstructed foams of equivalent microstructure. A statistical treatment based on the integral range provides confidence intervals for the estimated ETC. For foam samples with random homogeneous porosity, the mixed boundary conditions are shown to fulfill the macrohomogeneity condition and thus provide thermodynamically valid ETC estimates. For periodic foams with irregular microstructure, the ETC is very slightly underestimated under the mixed boundary conditions. For nonperiodic geometries, it is shown that periodic boundary conditions-commonly viewed as the referenceunderestimate the ETC due to boundary geometry mismatch, while the mixed boundary conditions give a more accurate and precise estimate. |
| Databáze: | OpenAIRE |
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