Documents disponibles écrits par cet auteur

Decomposition of Flow Structures in Stirred Reactors and Implications for Mixing Enhancement / Andrea Ducci in Industrial & engineering chemistry research, Vol. 47 N°10 (Mai 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3664-3676 Titre : Decomposition of Flow Structures in Stirred Reactors and Implications for Mixing Enhancement Type de document : texte imprimé Auteurs : Andrea Ducci, Auteur ; Zacharias Doulgerakis, Auteur ; Michael Yianneskis, Auteur Année de publication : 2008 Article en page(s) : p. 3664-3676 Langues : Anglais (eng) Mots-clés : Macro-instability  (MI)  ;Physical Résumé : Earlier studies have shown that macro-instability (MI) vortices in vessels stirred by radial flow impellers can be employed to improve mixing performance through guided feed insertion at selected radial positions along the path of a MI vortex, with an associated mixing time reduction of 20−30%. The present investigation provides for the first time an understanding of the physical mechanisms underlying the MI vortex phenomena, employing a proper orthogonal decomposition analysis to identify and characterize the different flow structures. It is shown that the MI structure is affected by an off-centering perturbation of the core and a stretching mechanism that interact in different ways for low, transitional, and high Reynolds numbers (Re). The different MI vortex frequencies phenomenologically identified in previous works and especially the two simultaneous frequencies encountered for transitional Re are shown to result from a competition between the two mechanisms. The implications of the fadings for mixing enhancement at different Re ranges are discussed. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie070905m [article] Decomposition of Flow Structures in Stirred Reactors and Implications for Mixing Enhancement [texte imprimé] / Andrea Ducci, Auteur ; Zacharias Doulgerakis, Auteur ; Michael Yianneskis, Auteur . - 2008 . - p. 3664-3676. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3664-3676 Mots-clés : Macro-instability  (MI)  ;Physical Résumé : Earlier studies have shown that macro-instability (MI) vortices in vessels stirred by radial flow impellers can be employed to improve mixing performance through guided feed insertion at selected radial positions along the path of a MI vortex, with an associated mixing time reduction of 20−30%. The present investigation provides for the first time an understanding of the physical mechanisms underlying the MI vortex phenomena, employing a proper orthogonal decomposition analysis to identify and characterize the different flow structures. It is shown that the MI structure is affected by an off-centering perturbation of the core and a stretching mechanism that interact in different ways for low, transitional, and high Reynolds numbers (Re). The different MI vortex frequencies phenomenologically identified in previous works and especially the two simultaneous frequencies encountered for transitional Re are shown to result from a competition between the two mechanisms. The implications of the fadings for mixing enhancement at different Re ranges are discussed. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie070905m

Three-dimensional deformation dynamics of trailing vortex structures in a stirred vessel / Yann Bouremel in Industrial & engineering chemistry research, Vol. 48 N° 17 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8148–8158 Titre : Three-dimensional deformation dynamics of trailing vortex structures in a stirred vessel Type de document : texte imprimé Auteurs : Yann Bouremel, Auteur ; Michael Yianneskis, Auteur ; Andrea Ducci, Auteur Année de publication : 2009 Article en page(s) : pp. 8148–8158 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Three-dimensional  deformation  dynamics  Vortical  structures  Stirred  vessels Résumé : Novel three-dimensional methodologies suitable for the characterization and quantification of the deformation dynamics resulting from vortical structures in stirred vessels are presented. The analytical approaches are developed in the context of the three-dimensional deformation encountered by a spherical fluid element in the vicinity of the trailing vortices around a Rushton impeller and allow the identification of the rate and type of dynamics (stretching, compression, biaxial strain, or biaxial compression) encountered by such an element in the vortex flow field, as well as the resulting surface deformation at different parts of the vortex. The results facilitate a more in-depth understanding of the deformation processes involved in fluid mixing in a stirred vessel, and their implications for enhancement of mixing in such processes are discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801481v [article] Three-dimensional deformation dynamics of trailing vortex structures in a stirred vessel [texte imprimé] / Yann Bouremel, Auteur ; Michael Yianneskis, Auteur ; Andrea Ducci, Auteur . - 2009 . - pp. 8148–8158. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8148–8158 Mots-clés : Three-dimensional  deformation  dynamics  Vortical  structures  Stirred  vessels Résumé : Novel three-dimensional methodologies suitable for the characterization and quantification of the deformation dynamics resulting from vortical structures in stirred vessels are presented. The analytical approaches are developed in the context of the three-dimensional deformation encountered by a spherical fluid element in the vicinity of the trailing vortices around a Rushton impeller and allow the identification of the rate and type of dynamics (stretching, compression, biaxial strain, or biaxial compression) encountered by such an element in the vortex flow field, as well as the resulting surface deformation at different parts of the vortex. The results facilitate a more in-depth understanding of the deformation processes involved in fluid mixing in a stirred vessel, and their implications for enhancement of mixing in such processes are discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801481v