Thestatistical behaviours of the instantaneous scalar dissipation rateNc of reaction progress variable c in turbulent premixed flames\nhave been analysed based on three-dimensional direct numerical simulation data of freely propagating statistically planar flame and\nV-flame configurations with different turbulent Reynolds number Ret. The statistical behaviours of Nc and different terms of its\ntransport equation for planar and V-flames are found to be qualitatively similar. The mean contribution of the density-variation\nterm T1 is positive, whereas the molecular dissipation term (-D2) acts as a leading order sink. The mean contribution of the strain\nrate term T2 is predominantly negative for the cases considered here. The mean reaction rate contribution T3 is positive (negative)\ntowards the unburned (burned) gas side of the flame, whereas the mean contribution of the diffusivity gradient term (D) assumes\nnegative (positive) values towards the unburned (burned) gas side. The local statistical behaviours of Nc, T1, T2, T3, (-D2), and\nf(D) have been analysed in terms of their marginal probability density functions (pdfs) and their joint pdfs with local tangential\nstrain rate aT and curvature Km. Detailed physical explanations have been provided for the observed behaviour.
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