Effect of material anisotropy on the fingering instability in reverse smouldering combustion

E.R. Ijioma, A. Muntean, T. Ogawa

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)

Abstract

It is well known from experiments that a sample of thin porous material burning against an oxidizing air under microgravity exhibits various finger-like char patterns. The patterns are classified into three distinct types depending on the oxidizer flow rate. (I) Sparse fingers; (II) tip-splitting fingers; (III) connected front. We presently extend our modeling strategy based on the homogenization approach, which has been applied for the case of isotropic porous media, to analyze the pattern behavior on anisotropic porous media. In order to understand the characteristic features of the patterns based on the influence of the local structure, we simply rely on fixed anisotropic two-dimensional geometries representative of the microstructure of interest. Thus, we illustrate numerically the consequence of the material anisotropy on the fingering patterns based on effective diffusion tensors calculated using the homogenization method and the mechanism of thermal-diffusion instability. Besides revealing new insights on the experimental observations, our numerical results show that material anisotropy can influence the uniformity on the patterns, but the distinct fingering regimes are independent of the local microstructure of materials. This effect is consistent with the qualitative experimental findings from Zik and Moses (1999). Keywords: Reverse smoldering; Anisotropy; Homogenization; Combustion instability; Fingering pattern
LanguageEnglish
Pages924-938
Number of pages15
JournalInternational Journal of Heat and Mass Transfer
Volume81
DOIs
StatePublished - 2015

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Reverse combustion
smoldering
Porous materials
Anisotropy
anisotropy
Homogenization method
homogenizing
Microstructure
Thermal diffusion
Microgravity
Tensors
Flow rate
Geometry
combustion stability
microstructure
Air
oxidizers
thermal diffusion
porous materials
microgravity

Cite this

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title = "Effect of material anisotropy on the fingering instability in reverse smouldering combustion",
abstract = "It is well known from experiments that a sample of thin porous material burning against an oxidizing air under microgravity exhibits various finger-like char patterns. The patterns are classified into three distinct types depending on the oxidizer flow rate. (I) Sparse fingers; (II) tip-splitting fingers; (III) connected front. We presently extend our modeling strategy based on the homogenization approach, which has been applied for the case of isotropic porous media, to analyze the pattern behavior on anisotropic porous media. In order to understand the characteristic features of the patterns based on the influence of the local structure, we simply rely on fixed anisotropic two-dimensional geometries representative of the microstructure of interest. Thus, we illustrate numerically the consequence of the material anisotropy on the fingering patterns based on effective diffusion tensors calculated using the homogenization method and the mechanism of thermal-diffusion instability. Besides revealing new insights on the experimental observations, our numerical results show that material anisotropy can influence the uniformity on the patterns, but the distinct fingering regimes are independent of the local microstructure of materials. This effect is consistent with the qualitative experimental findings from Zik and Moses (1999). Keywords: Reverse smoldering; Anisotropy; Homogenization; Combustion instability; Fingering pattern",
author = "E.R. Ijioma and A. Muntean and T. Ogawa",
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doi = "10.1016/j.ijheatmasstransfer.2014.11.021",
language = "English",
volume = "81",
pages = "924--938",
journal = "International Journal of Heat and Mass Transfer",
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}

Effect of material anisotropy on the fingering instability in reverse smouldering combustion. / Ijioma, E.R.; Muntean, A.; Ogawa, T.

In: International Journal of Heat and Mass Transfer, Vol. 81, 2015, p. 924-938.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Effect of material anisotropy on the fingering instability in reverse smouldering combustion

AU - Ijioma,E.R.

AU - Muntean,A.

AU - Ogawa,T.

PY - 2015

Y1 - 2015

N2 - It is well known from experiments that a sample of thin porous material burning against an oxidizing air under microgravity exhibits various finger-like char patterns. The patterns are classified into three distinct types depending on the oxidizer flow rate. (I) Sparse fingers; (II) tip-splitting fingers; (III) connected front. We presently extend our modeling strategy based on the homogenization approach, which has been applied for the case of isotropic porous media, to analyze the pattern behavior on anisotropic porous media. In order to understand the characteristic features of the patterns based on the influence of the local structure, we simply rely on fixed anisotropic two-dimensional geometries representative of the microstructure of interest. Thus, we illustrate numerically the consequence of the material anisotropy on the fingering patterns based on effective diffusion tensors calculated using the homogenization method and the mechanism of thermal-diffusion instability. Besides revealing new insights on the experimental observations, our numerical results show that material anisotropy can influence the uniformity on the patterns, but the distinct fingering regimes are independent of the local microstructure of materials. This effect is consistent with the qualitative experimental findings from Zik and Moses (1999). Keywords: Reverse smoldering; Anisotropy; Homogenization; Combustion instability; Fingering pattern

AB - It is well known from experiments that a sample of thin porous material burning against an oxidizing air under microgravity exhibits various finger-like char patterns. The patterns are classified into three distinct types depending on the oxidizer flow rate. (I) Sparse fingers; (II) tip-splitting fingers; (III) connected front. We presently extend our modeling strategy based on the homogenization approach, which has been applied for the case of isotropic porous media, to analyze the pattern behavior on anisotropic porous media. In order to understand the characteristic features of the patterns based on the influence of the local structure, we simply rely on fixed anisotropic two-dimensional geometries representative of the microstructure of interest. Thus, we illustrate numerically the consequence of the material anisotropy on the fingering patterns based on effective diffusion tensors calculated using the homogenization method and the mechanism of thermal-diffusion instability. Besides revealing new insights on the experimental observations, our numerical results show that material anisotropy can influence the uniformity on the patterns, but the distinct fingering regimes are independent of the local microstructure of materials. This effect is consistent with the qualitative experimental findings from Zik and Moses (1999). Keywords: Reverse smoldering; Anisotropy; Homogenization; Combustion instability; Fingering pattern

U2 - 10.1016/j.ijheatmasstransfer.2014.11.021

DO - 10.1016/j.ijheatmasstransfer.2014.11.021

M3 - Article

VL - 81

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JO - International Journal of Heat and Mass Transfer

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SN - 0017-9310

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