Direct quadrature method of moments for the mixing of inert polydisperse fluidized powders and the role of numerical diffusion / Luca Mazzei in Industrial & engineering chemistry research, Vol. 49 N° 11 (Juin 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp 5141–5152 Titre : Direct quadrature method of moments for the mixing of inert polydisperse fluidized powders and the role of numerical diffusion Type de document : texte imprimé Auteurs : Luca Mazzei, Auteur ; Daniele L. Marchisio, Auteur ; Paola Lettieri, Auteur Année de publication : 2010 Article en page(s) : pp 5141–5152 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Numerical diffusion Résumé : Computational fluid dynamics (CFD) is extensively employed to investigate dense fluidized suspensions. Most mathematical models assume that the powder is monodisperse or is formed by few solid phases of particles with constant size. Real powders, nevertheless, are polydisperse, with their particle size distribution continuously changing in time and space. To account for this important feature, models have to include a population balance equation (PBE), which needs to be solved along with the customary fluid dynamic transport equations. The recently developed direct quadrature method of moments (DQMOM) permits solving PBEs in commercial CFD codes at relatively low computational cost. This technique, nevertheless, still needs testing in the context of dense multiphase flows. In this work we implement DQMOM within the CFD code Fluent to study the mixing of two polydisperse fluidized suspensions initially segregated. Each node of the quadrature represents a distinct solid phase advected with its own velocity. Simulating this apparently simple system highlights a problem related to the numerical solution of the DQMOM transport equations: these do not feature diffusive terms, but the numerical diffusion generated by the finite-volume integration method alters the model predictions, leading to wrong results. To solve this, the PBE needs to account for diffusion: this yields source terms in the transport equations of the quadrature weights and nodes that ensure the latter are correctly predicted. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901116y [article] Direct quadrature method of moments for the mixing of inert polydisperse fluidized powders and the role of numerical diffusion [texte imprimé] / Luca Mazzei, Auteur ; Daniele L. Marchisio, Auteur ; Paola Lettieri, Auteur . - 2010 . - pp 5141–5152. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp 5141–5152 Mots-clés : Numerical diffusion Résumé : Computational fluid dynamics (CFD) is extensively employed to investigate dense fluidized suspensions. Most mathematical models assume that the powder is monodisperse or is formed by few solid phases of particles with constant size. Real powders, nevertheless, are polydisperse, with their particle size distribution continuously changing in time and space. To account for this important feature, models have to include a population balance equation (PBE), which needs to be solved along with the customary fluid dynamic transport equations. The recently developed direct quadrature method of moments (DQMOM) permits solving PBEs in commercial CFD codes at relatively low computational cost. This technique, nevertheless, still needs testing in the context of dense multiphase flows. In this work we implement DQMOM within the CFD code Fluent to study the mixing of two polydisperse fluidized suspensions initially segregated. Each node of the quadrature represents a distinct solid phase advected with its own velocity. Simulating this apparently simple system highlights a problem related to the numerical solution of the DQMOM transport equations: these do not feature diffusive terms, but the numerical diffusion generated by the finite-volume integration method alters the model predictions, leading to wrong results. To solve this, the PBE needs to account for diffusion: this yields source terms in the transport equations of the quadrature weights and nodes that ensure the latter are correctly predicted. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901116y

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