Dissipation element (DE) analysis is a method for analyzing scalar fields in turbulent flows. DEs are defined as a coherent region in which all gradient trajectories of a scalar field reach the same extremal points. Therefore, the scalar field can be compartmentalized in monotonous space-filling regions. The DE analysis is applied to a set of spatially evolving premixed jet flames at different Reynolds numbers. The simulations feature finite rate chemistry with 16 species and 73 reactions. The jet consists of a methane/air mixture with an equivalence ratio φ = 0.7. Statistics of DE parameters are shown and compared to those of a DNS of a non-reacting spatial jet, a non-reacting temporally evolving jet and isotropic homogeneous turbulence. The invariance of the normalized length distribution of the DEs toward changes in Reynolds number observed in non-reacting flows holds for the reacting cases and the characteristic scaling with Kolmogorov micro-scale is reproduced. Furthermore, the DE statistics reflect the influence of the premixed flame structure on the turbulent scalar fields.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors acknowledge funding from of the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement No 695747. In addition, the authors gratefully acknowledge the computing time provided by the JARA High Performance Computing Partition (JHPC09 and JHPC22) on the supercomputers JUQUEEN and JURECA at the Jülich Supercomputing Centre. This work was supported by the H2020 European Research Council [Advanced Grant (AdG), PE8, ERC-2015-AdG Milestone].