| A large eddy simulation based on the filtered vorticity transport equation has been coupled with the filtered mass weighted density function transport equation. The filtered vorticity transport has been formulated using the diffusion-velocity method and then solved using the vortex-in-cell scheme in conjunction with both Smagorinsky and dynamic eddy viscosity subgrid scale models for an anisotropic flow. The transport equation for filtered mass weighted density function is solved using the Lagrangian Monte-Carlo method. The methodology has been tested on both chemically reacting with no heat release and thermally stratified spatially growing mixing layers. It is shown that mixing has a greater effect on scalar field within the vortex structure as compared to the braid regions. Also for high Damkohler number (Da), the reaction zones are mainly limited to the thin reacting interfacial zones, i.e. the contact zone between the reactants, whereas for low Da, the reacting zones are spread as reacting pockets within the vortex structure. The effect of vorticity-temperature interaction, i.e., the volumetric expansion and baroclinic vorticity generation, on the flow field is also investigated by mixing a cold and a hot stream with temperature differences of 0, 5, 10, 30 and 50°K. The mixing layer is destabilized earlier and the pairing of vortical structures is reduced as temperature difference is increased. The characteristics of the flow field, i.e. the vorticity contours, the mean velocity, root-mean-square velocity fluctuations and negative cross-stream correlations are discussed. Also, the characteristics of the scalar field, i.e. the mean scalar profiles, root-mean-square scalar fluctuations profiles and filtered probability density function are presented. |
