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Characterizing relaxation timescales and overall steady-state efficiency of continuous inflow-outflow micromixers / S. Cerbelli in La Houille blanche, N° 6 (2009) 

Public ISBD [article]  in La Houille blanche > N° 6 (2009) . - pp. 135-142 Titre : Characterizing relaxation timescales and overall steady-state efficiency of continuous inflow-outflow micromixers Titre original : Caractérisation d'échelles de temps de relaxation et d'efficacité totale en régime permanent de micro mélangeurs à flux d'entrée-sortie continu Type de document : texte imprimé Auteurs : S. Cerbelli, Auteur ; M. Giona, Auteur ; F. Garofalo, Auteur Article en page(s) : pp. 135-142 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Microfluidique  Micro  mélangeurs  Systèmes  entrées-sorties Index. décimale : 551.4 Résumé : Most of the efforts for developing a consistent theory of mixing have mainly considered two classes of problems, namely mixing in closed bounded flows and dispersion in infinitely extended domains. However, microfluidic devices are typically bounded inflow-outflow systems, and a tailored approach to address quantitatively their mixing properties must be considered. Based on the spectral (eigenvalue-eigenfunction) structure of the advection-diffusion operator, we develop a quantitative framework for describing both transient and steady-state mixing in open flow devices. We show that the relaxation timescale for reaching the steady state condition can be conveniently quantified by the Frobenius eigenvalue of the advection-diffusion operator associated with the assigned boundary value problem. The steady-state homogenization process along the mean streamwise direction of the mixer can instead be approached by considering the spectral properties of the linear operator that maps the inlet profile into the corresponding profile at the generic mixer cross-section. Concrete examples of physically realizable flows, ranging from a simple 2d channel flows to a three-dimensional helical flow giving rise to complex kinematic structures are thoroughly analyzed and used as benchmark test cases to illustrate the spectral characterization of mixing flow devices. DEWEY : 553.7 ISSN : 0018-6368 En ligne : http://www.shf-lhb.org/index.php?option=article&access=standard&Itemid=129&url=/ [...] [article] Characterizing relaxation timescales and overall steady-state efficiency of continuous inflow-outflow micromixers = Caractérisation d'échelles de temps de relaxation et d'efficacité totale en régime permanent de micro mélangeurs à flux d'entrée-sortie continu [texte imprimé] / S. Cerbelli, Auteur ; M. Giona, Auteur ; F. Garofalo, Auteur . - pp. 135-142. Hydraulique Langues : Anglais (eng) in La Houille blanche > N° 6 (2009) . - pp. 135-142 Mots-clés : Microfluidique  Micro  mélangeurs  Systèmes  entrées-sorties Index. décimale : 551.4 Résumé : Most of the efforts for developing a consistent theory of mixing have mainly considered two classes of problems, namely mixing in closed bounded flows and dispersion in infinitely extended domains. However, microfluidic devices are typically bounded inflow-outflow systems, and a tailored approach to address quantitatively their mixing properties must be considered. Based on the spectral (eigenvalue-eigenfunction) structure of the advection-diffusion operator, we develop a quantitative framework for describing both transient and steady-state mixing in open flow devices. We show that the relaxation timescale for reaching the steady state condition can be conveniently quantified by the Frobenius eigenvalue of the advection-diffusion operator associated with the assigned boundary value problem. The steady-state homogenization process along the mean streamwise direction of the mixer can instead be approached by considering the spectral properties of the linear operator that maps the inlet profile into the corresponding profile at the generic mixer cross-section. Concrete examples of physically realizable flows, ranging from a simple 2d channel flows to a three-dimensional helical flow giving rise to complex kinematic structures are thoroughly analyzed and used as benchmark test cases to illustrate the spectral characterization of mixing flow devices. DEWEY : 553.7 ISSN : 0018-6368 En ligne : http://www.shf-lhb.org/index.php?option=article&access=standard&Itemid=129&url=/ [...]