Effects of unsteady strain rate on scalar dissipation structures in turbulent planar jets

An analysis of previously acquired experimental data is performed with the objective of investigating the relationship between strain rate and scalar dissipation rate structures in gas-phase turbulent planar jet flows at local Reynolds numbers ranging from 1000 to 6100. The data analyzed were simultaneously acquired two-dimensional (2D) velocity and 2D conserved scalar fields. The measurements show that, in agreement with previous work, the scalar dissipation structures tend to align orthogonally to the axis of the principal compressive strain rate, and the magnitude of the strain rates acting on the dissipation layers is consistent with theoretical turbulent inner-scale values. Furthermore, the spatially resolved data show that profiles of scalar dissipation, taken across the sheet-like scalar dissipation structures, are approximately Gaussian, whereas the strain rate profiles across the same structures exhibit no characteristic shape, and rarely reach a maximum at the same location as the scalar dissipa...