Large Scale Geometrical Aspects of Turbulent Jet Scalar Regions and Interfaces: Measurement and Modeling

This study focuses on the measurement and modeling of large scale geometrical aspects of turbulent jet scalar regions and interfaces. While several previous studies have focused on the small scale geometrical properties using fractal ideas, examination of the large scale geometrical aspects requires the development of what we call generalized fractals, i.e. the scale-dependent generalization of the original self-similar geometric framework. Our work involves the purely meshless approach to the determination of the generalized fractal properties, pioneered by Catrakis, that eliminates the need for grid-based box counting. We investigate the purely meshless generalized fractal approach using experimental databases generated in our laboratories on fully-developed turbulent jets with a Reynolds number of Re ∼ 20,000 and a Schmidt number of Sc ∼ 2,000. In our approach, we examine the dependence of the generalized fractal aspects of the turbulent interfaces at various spatial resolution scales. Our results indicate that the large scale geometrical aspects are strongly scale dependent and amenable to modeling using generalized fractal functions.