Local Strain Rate and Curvature Dependences of Scalar Dissipation Rate Transport in Turbulent Premixed Flames: A Direct Numerical Simulation Analysis. (3rd April 2014)

• Record Type: Journal Article
• Authors: Gao, Y.; Chakraborty, N.; Swaminathan, N.
• Other Names: Fairweather Michael Academic Editor.
• Is Part Of: Journal of combustion. Volume 2014(2014)
• Publication Date: 2014-04-03
• Subjects: Combustion -- Periodicals; 541.36105
• DOI: 10.1155/2014/280671
• Languages: English
• ISSNs: 2090-1968

Abstract

Abstract : The statistical behaviours of the instantaneous scalar dissipation rateN c of reaction progress variablec in turbulent premixed flames have been analysed based on three-dimensional direct numerical simulation data of freely propagating statistically planar flame and V-flame configurations with different turbulent Reynolds numberRe t . The statistical behaviours ofN c and different terms of its transport equation for planar and V-flames are found to be qualitatively similar. The mean contribution of the density-variation termT 1 is positive, whereas the molecular dissipation term( - D 2 ) acts as a leading order sink. The mean contribution of the strain rate termT 2 is predominantly negative for the cases considered here. The mean reaction rate contributionT 3 is positive (negative) towards the unburned (burned) gas side of the flame, whereas the mean contribution of the diffusivity gradient term( D ) assumes negative (positive) values towards the unburned (burned) gas side. The local statistical behaviours ofN c, T 1, T 2, T 3, ( - D 2 ), andf ( D ) have been analysed in terms of their marginal probability density functions (pdfs) and their joint pdfs with local tangential strain ratea T and curvaturek m . Detailed physical explanations have been provided for the observed behaviour.