Entropy Generation in the Viscous Layer ofa Turbulent Channel Flow. 5th International Symposium on Turbulence, Heat and Mass Transfer (THMT-5).

McEligot, D. M. ; Walsh, E. J. ; Laurien, E.

Technical Information Center Oak Ridge Tennessee

关键词: Entropy;    Turbulence;    Channel flow;    Friction;    Kinetic energy;   

RP-ID  :  DE2007911191

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

The local (pointwise) entropy generation rate per unit volume S is a key to improving many energy processes and applications. Entropy generation due to friction occurs from viscous dissipation of mean-flow kinetic energy (called 'direct dissipation') and dissipation of turbulent kinetic energy into thermal energy ('indirect' or turbulent dissipation). The objective of the present study is to compare two approaches for the prediction of S for the viscous layer in near asymptotic (high Reynolds number) turbulent flows. By employing available direct numerical simulations (DNS) it was found that about two-thirds of the entropy generation occurs in this layer. A popular approximate approach does not agree with the result from the more exact evaluation of S but its integral falls within about four per cent at the edge of the viscous layer.