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A narrow band-based multiscale multigroup full-spectrum k-distribution method for radiative transfer in nonhomogeneous gas-soot mixtures / Gopalendu Pal in Journal of heat transfer, Vol. 132 N° 2 (n° spécial) (Fevrier 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 2 (n° spécial) (Fevrier 2010) . - pp. [023307-1/9] Titre : A narrow band-based multiscale multigroup full-spectrum k-distribution method for radiative transfer in nonhomogeneous gas-soot mixtures Type de document : texte imprimé Auteurs : Gopalendu Pal, Auteur ; Michael F. Modest, Auteur Article en page(s) : pp. [023307-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Absorption  coefficients  Combustion  Flames  Gas  mixtures  Heat  transfer  Radiative  transfer Index. décimale : 536 Chaleur. Thermodynamique Résumé : The full-spectrum k-distribution (FSK) approach has become a promising method for radiative heat transfer calculations in strongly nongray participating media, due to its ability to achieve high accuracy at a tiny fraction of the line-by-line (LBL) computational cost. However, inhomogeneities in temperature, total pressure, and component mole fractions severely challenge the accuracy of the FSK approach. The objective of this paper is to develop a narrow band-based hybrid FSK model that is accurate for radiation calculations in combustion systems containing both molecular gases and nongray particles such as soot with strong temperature and mole fraction inhomogeneities. This method combines the advantages of the multigroup FSK method for temperature inhomogeneities in a single species, and the modified multiscale FSK method for concentration inhomogeneities in gas-soot mixtures. In this new method, each species is considered as one scale; the absorption coefficients within each narrow band of every gas scale are divided into M exclusive spectral groups, depending on their temperature dependence. Accurate and compact narrow band multigroup databases are constructed for combustion gases such as CO2 and H2O. Sample calculations are performed for a 1D medium and also for a 2D axisymmetric combustion flame. The narrow band-based hybrid method is observed to accurately predict heat transfer from extremely inhomogeneous gas-soot mixtures with/without wall emission, yielding close-to-LBL accuracy. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] A narrow band-based multiscale multigroup full-spectrum k-distribution method for radiative transfer in nonhomogeneous gas-soot mixtures [texte imprimé] / Gopalendu Pal, Auteur ; Michael F. Modest, Auteur . - pp. [023307-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 2 (n° spécial) (Fevrier 2010) . - pp. [023307-1/9] Mots-clés : Absorption  coefficients  Combustion  Flames  Gas  mixtures  Heat  transfer  Radiative  transfer Index. décimale : 536 Chaleur. Thermodynamique Résumé : The full-spectrum k-distribution (FSK) approach has become a promising method for radiative heat transfer calculations in strongly nongray participating media, due to its ability to achieve high accuracy at a tiny fraction of the line-by-line (LBL) computational cost. However, inhomogeneities in temperature, total pressure, and component mole fractions severely challenge the accuracy of the FSK approach. The objective of this paper is to develop a narrow band-based hybrid FSK model that is accurate for radiation calculations in combustion systems containing both molecular gases and nongray particles such as soot with strong temperature and mole fraction inhomogeneities. This method combines the advantages of the multigroup FSK method for temperature inhomogeneities in a single species, and the modified multiscale FSK method for concentration inhomogeneities in gas-soot mixtures. In this new method, each species is considered as one scale; the absorption coefficients within each narrow band of every gas scale are divided into M exclusive spectral groups, depending on their temperature dependence. Accurate and compact narrow band multigroup databases are constructed for combustion gases such as CO2 and H2O. Sample calculations are performed for a 1D medium and also for a 2D axisymmetric combustion flame. The narrow band-based hybrid method is observed to accurately predict heat transfer from extremely inhomogeneous gas-soot mixtures with/without wall emission, yielding close-to-LBL accuracy. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Spectral module for photon Monte Carlo calculations in hypersonic nonequilibrium radiation / Takashi Ozawa in Journal of heat transfer, Vol. 132 N° 2 (n° spécial) (Fevrier 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 2 (n° spécial) (Fevrier 2010) . - pp. [023406-1/8] Titre : Spectral module for photon Monte Carlo calculations in hypersonic nonequilibrium radiation Type de document : texte imprimé Auteurs : Takashi Ozawa, Auteur ; Michael F. Modest, Auteur ; Deborah A. Levin, Auteur Article en page(s) : pp. [023406-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Monte  Carlo  methods  Nonequilibrium  Radiation  QSS  Hypersonic  flow  Absorption  coefficients  Flow  simulation  Molecular  electronic  states Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this paper, efficient spectral modules and random number databases are developed for atomic and diatomic species for use in photon Monte Carlo (PMC) modeling of hypersonic nonequilibrium flow radiation. To model nonequilibrium flow conditions, the quasisteady state assumption was used to generate electronic state populations of atomic and diatomic gas species in the databases. For atomic species (N and O), both bound-bound transitions and continuum radiation were included and were separately databased as a function of electron temperature and number density as well as the ratio of atomic ion to neutral number density. For the radiating diatomic species of N2+, N2, O2, and NO databases were generated for each electronic molecular electronic system. In each molecular electronic system, the rovibrational transition lines were separately databased for each electronic upper state population forming the electronic system. The spectral module for the PMC method was optimized toward computational efficiency for emission calculations, wavelength selections of photon bundles and absorption coefficient calculations in the ray tracing scheme. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Spectral module for photon Monte Carlo calculations in hypersonic nonequilibrium radiation [texte imprimé] / Takashi Ozawa, Auteur ; Michael F. Modest, Auteur ; Deborah A. Levin, Auteur . - pp. [023406-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 2 (n° spécial) (Fevrier 2010) . - pp. [023406-1/8] Mots-clés : Monte  Carlo  methods  Nonequilibrium  Radiation  QSS  Hypersonic  flow  Absorption  coefficients  Flow  simulation  Molecular  electronic  states Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this paper, efficient spectral modules and random number databases are developed for atomic and diatomic species for use in photon Monte Carlo (PMC) modeling of hypersonic nonequilibrium flow radiation. To model nonequilibrium flow conditions, the quasisteady state assumption was used to generate electronic state populations of atomic and diatomic gas species in the databases. For atomic species (N and O), both bound-bound transitions and continuum radiation were included and were separately databased as a function of electron temperature and number density as well as the ratio of atomic ion to neutral number density. For the radiating diatomic species of N2+, N2, O2, and NO databases were generated for each electronic molecular electronic system. In each molecular electronic system, the rovibrational transition lines were separately databased for each electronic upper state population forming the electronic system. The spectral module for the PMC method was optimized toward computational efficiency for emission calculations, wavelength selections of photon bundles and absorption coefficient calculations in the ray tracing scheme. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]