Structure and scaling of high Reynolds number turbulent boundary layers

Abstract: Wall-bounded turbulent flows are pervasive in nature and are also encountered in several engineering applications. A dominant feature-type present within these flows are the recurring eddies or so-called coherent structures, that are highly three-dimensional (3-D) in geometry and are statistically significant over a wide range of scales. This has led to the proposal of various coherent structure-based models in the literature, with the attached eddy model (AEM) of wall-turbulence being the most popular amongst them.
In this talk, I will present a unique set of (i) multi-point hotwire and (ii) large-scale PIV measurements conducted in a high Reynolds number turbulent boundary layer, which have facilitated reconstruction of the 3-D statistical picture of its energy-containing eddies. The measurements reveal universality in the 3-D geometry of these eddies across various Reynolds number, as well as across all canonical wall-bounded flows. Further, these investigations provide direct empirical support towards the AEM, with the prospect of further enhancing its efficacy based on data-driven estimates.

Bio: Rahul studied Mechanical and Aerospace Engineering at the Indian Institutes of Technology (IITs), for his Bachelors and Masters degrees in 2014 and 2016, respectively. He completed his PhD in June 2021 at the University of Melbourne, under the supervision of Profs. Ivan Marusic and Jason Monty. He was awarded a three-year Melbourne Postdoctoral Fellowship in January 2023, during which he is researching active and passive turbulent drag reduction techniques and non-canonical wall-bounded flows.