A Brownian motion algorithm for tow scale modeling of chemical vapor infiltration

Vignoles, Gérard L.; Ros, William; Szelengowicz, Ivan; Germain, Christian

doi:10.1016/j.commatsci.2011.01.031

Cited by 18 publications

(7 citation statements)

References 26 publications

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“…Developed for dispersion of solutes in underground aquifers [34], this scheme has also been validated when applied to the simulation of gas infiltration in porous media [30], a totally analogous problem.…”

Section: Itō-taylor Random Walkmentioning

confidence: 99%

“…In such a case, a direct simulation of species transport (phonons or molecules) is performed. However, another random walk method can be used, which is the simulation of Brownian motion at a larger scale than that of the absorption length [28][29][30]: it is adapted to solve the energy equation or whatever similar elliptical equation (pressure equation for groundwater flow, mass di↵usion equation, etc), but in it the transported species is not any more the direct simulation of an "energy carrier". An interesting advantage of this method is that it takes quite naturally into account the local media anisotropy.…”

Section: Introductionmentioning

confidence: 99%

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A hybrid random walk method for the simulation of coupled conduction and linearized radiation transfer at local scale in porous media with opaque solid phases

Vignoles

2016

International Journal of Heat and Mass Transfer

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International audienceHeat transfer properties from ambient up to extremely high temperatures are a key feature of advanced thermal protection and thermal exchange materials – like ceramic foams or fiber assemblies. Because of their porous nature, heat transfer rests not only on conduction in opaque solids and on convection in pores, but also on radiation trough pores. The precise knowledge of the thermal behavior of these materials in these conditions is an issue. In a ”virtual material” framework, we present a computational simulation tool for heat transfer in such materials, combining solid-phase conduction and linearized radiative transfer in open or closed radiating cavities with opaque interfaces. The software is suited to working in large 3D blocks as produced e. g. by X-ray CMT or by image synthesis. An original Monte-Carlo Mixed Random Walks scheme accounting for both diffusion and radiation is presented and validated. The application to a real image of a fibrous medium is described and discussed, principally in terms of the influence of the diffusion/radiation ratio on the effective (large-scale) diffusivity tensor

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Section: Itō-taylor Random Walkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A hybrid random walk method for the simulation of coupled conduction and linearized radiation transfer at local scale in porous media with opaque solid phases

Vignoles

2016

International Journal of Heat and Mass Transfer

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“…In recent years, Vignoles imaged raw and partially densified stitched cloth layup composites using CMT at both low and high resolutions, providing the structural, gas, and heat transport properties . Later, he developed complete multiscale algorithms to simulate the reactive precursor gases transport in preforms . Bale imaged three‐dimensional woven composites using X‐ray μCT and studied the tow geometry statistically.…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12] Later, he developed complete multiscale algorithms to simulate the reactive precursor gases transport in preforms. [13][14][15] Bale 16 imaged three-dimensional woven composites using X-ray lCT and studied the tow geometry statistically.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Pore Structure Evolution Between Bundles of Plain Woven Fabrics During Chemical Vapor Infiltration Process: The Influence of Preform Geometry

et al. 2012

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A three‐dimensional model combining the nonconservative level set method and the steady‐state diffusion equation is presented for studying evolving pore structure between bundles of plain woven fabrics during chemical vapor infiltration process. Parametric studies have been conducted to determine the sensitivity of the evolution of structural properties and effective gas diffusion coefficients to the geometric parameters of the preform. Based on our results, some analytical expressions are proposed to estimate the evolution of structural properties and the tortuosity. The prediction of the presented models is well consistent with the existing data of experiments.

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“…flow through the furnace. These gases decompose into heterocyclic carbon ring compounds [18,31] and deposit on the surface to form graphite-like structures with varying texture degrees. This form of carbon is termed PyC and exhibits transverse microstructural isotropy in the deposition plane [27].…”

Section: Introductionmentioning

confidence: 99%

Homogenization of the elastic properties of pyrolytic carbon based on an image processing technique

et al. 2012

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In this work, the linear elastic material properties of differently textured variants of pyrolytic carbon are homogenized from the submicro-to the micro-scale. In high resolution transmission electron microscope (HRTEM) lattice fringe images, the microstructure of pyrolytic carbon manifests itself in terms of projections of graphene layers. According to their orientation distribution, different textures of pyrolytic carbon have been classified. Assuming a von Mises-Fisher distribution for the spatial orientation of single graphene layers, the orientation distribution function of the projected layers in the image plane is analytically found to be a modified Struve function. For each pyrolytic carbon texture, Maximum-likelihood estimates for the mean orientation and the concentration parameter of the von Mises-Fisher distribution are obtained numerically. Hereby, Fourier transformation and appropriate filters are used to determine the probabilities for discrete orientations of the graphene layers directly from HRTEM images. First-and second-order bounds of the linear elastic properties of pyrolytic carbon of the different textures are computed. Elastic constants of graphite and pyrolytic graphite have been used for modeling the elastic behavior of the graphene layers within a continuum mechanical setting. Due to the high anisotropy of all analyzed textures of pyrolytic carbon, the differences even between the second-order bounds are quite large.Notation. A direct tensor notation is preferred throughout the text. If tensor components are used, then the Einstein summation convention is applied. Vectors and 2nd-order tensors are denoted by lowercase and uppercase bold letters, e.g., a and A, respectively. A linear mapping of 2nd-order tensors by a 4th-order tensor is written as A = C[B]. The scalar product

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A Brownian motion algorithm for tow scale modeling of chemical vapor infiltration

Cited by 18 publications

References 26 publications

A hybrid random walk method for the simulation of coupled conduction and linearized radiation transfer at local scale in porous media with opaque solid phases

A hybrid random walk method for the simulation of coupled conduction and linearized radiation transfer at local scale in porous media with opaque solid phases

Modeling of Pore Structure Evolution Between Bundles of Plain Woven Fabrics During Chemical Vapor Infiltration Process: The Influence of Preform Geometry

Homogenization of the elastic properties of pyrolytic carbon based on an image processing technique

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