Prediction of the turbulent prandtl number in wall flows with lagrangian simulations / Chiranth Srinivasan in Industrial & engineering chemistry research, Vol. 50 N° 15 (Août 2011)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 8881-8891 Titre : Prediction of the turbulent prandtl number in wall flows with lagrangian simulations Type de document : texte imprimé Auteurs : Chiranth Srinivasan, Auteur ; Dimitrios V. Papavassiliou, Auteur Année de publication : 2011 Article en page(s) : pp. 8881-8891 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Prandtl number Prediction Résumé : The turbulent Prandtl number (Prt) is an important parameter in modeling turbulent transport, and a lot of effort has been placed in studying its behavior in wall turbulence. This work applied the Churchill model for turbulence scaling to determine the Prt. Two different computational approaches involving a direct numerical simulation in conjunction with Lagrangian techniques were utilized. In the first approach, the local fractions of shear stress and heat flux density, as defined using Churchill's scaling model and determined previously by Le and Papavassiliou [Le, P. M.; Papavassiliou, D. V. On temperature prediction at low Re turbulent flows using the Churchill turbulent heat flux correlation. Int. J. Heat Mass Transfer. 2006, 49, 3681-3690], were used to calculate the Prt. For Poiseuille channel flow, the Prt, at distances far away from the channel walls, was found to have a value between 0.8 and 0.9 irrespective of the molecular Prandtl number, while for plane Couette flow, it was found to be between 0.7 and 1.5. An alternative approach to determining the Pr, is to translate Churchill's physical interpretation of Pr, in a Lagrangian sense. Contributions of turbulent and molecular transport to momentum and heat transfer were calculated to find the local fractions of shear stress and heat flux density. For both Poiseuille channel and Couette flows, the Prt at Pr= 0.1 in regions near the center of the channel was higher than that at higher Pr. For Pr > 0.7, in the case of Poiseuille flow and plane Couette flow, the Prt started from values above 1 decreased and then followed a similar trend to that of the lower molecular Pr. The near-wall Prt increased with increasing Pr for both types of turbulent flow. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24395833 [article] Prediction of the turbulent prandtl number in wall flows with lagrangian simulations [texte imprimé] / Chiranth Srinivasan, Auteur ; Dimitrios V. Papavassiliou, Auteur . - 2011 . - pp. 8881-8891. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 8881-8891 Mots-clés : Prandtl number Prediction Résumé : The turbulent Prandtl number (Prt) is an important parameter in modeling turbulent transport, and a lot of effort has been placed in studying its behavior in wall turbulence. This work applied the Churchill model for turbulence scaling to determine the Prt. Two different computational approaches involving a direct numerical simulation in conjunction with Lagrangian techniques were utilized. In the first approach, the local fractions of shear stress and heat flux density, as defined using Churchill's scaling model and determined previously by Le and Papavassiliou [Le, P. M.; Papavassiliou, D. V. On temperature prediction at low Re turbulent flows using the Churchill turbulent heat flux correlation. Int. J. Heat Mass Transfer. 2006, 49, 3681-3690], were used to calculate the Prt. For Poiseuille channel flow, the Prt, at distances far away from the channel walls, was found to have a value between 0.8 and 0.9 irrespective of the molecular Prandtl number, while for plane Couette flow, it was found to be between 0.7 and 1.5. An alternative approach to determining the Pr, is to translate Churchill's physical interpretation of Pr, in a Lagrangian sense. Contributions of turbulent and molecular transport to momentum and heat transfer were calculated to find the local fractions of shear stress and heat flux density. For both Poiseuille channel and Couette flows, the Prt at Pr= 0.1 in regions near the center of the channel was higher than that at higher Pr. For Pr > 0.7, in the case of Poiseuille flow and plane Couette flow, the Prt started from values above 1 decreased and then followed a similar trend to that of the lower molecular Pr. The near-wall Prt increased with increasing Pr for both types of turbulent flow. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24395833

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