AME Seminar: Gokul Pathikonda
Thursday, April 4, 2024 - 4:00 p.m.
Gokul Pathikonda
Assistant Professor
School for Engineering of Matter, Transport and Energy
Arizona State University
"Mixing and Separation in Turbulent Boundary Layers over Textured Surfaces"
AME Lecture Hall, Room S212 | Zoom link
Abstract: Recent advances in optical diagnostics have enabled us to make highly resolved field measurements (spatially and temporally) in complex turbulent environments that were previously not amenable to conventional techniques. For this seminar, we will present two examples where this progress has provided novel perspectives of the complex interplay of turbulent scales. First, we look at the dispersion of a passive scalar plume that is injected into a high Reynolds number (Re) turbulent boundary layer using simultaneous planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV). We focus on the role of the large coherent structures that populate such boundary layers on the break-up, meandering, and dispersion of the scalar plume at early stage. These structures significantly alter the long-range intermittency and instantaneous concentrations further downstream – understanding which is critical for modeling pollutant, aerosol, and particulate transport in atmospheric boundary layers over complex terrains. In a second contrasting example, we will discuss the ability of surface texturing to induce large scale secondary flows and alter the coherent motions within the boundary layer via intentional heterogeneities in surface skin-friction. Engineering these surfaces will provide an ability to control the bulk boundary layer behavior such as separation, scalar transport, etc. To demonstrate this, we discuss a class of herringbone-type 2D and 3D roughness patterns, and their induced changes to the separation behavior over a hump.
Bio: Dr. Gokul Pathikonda is an assistant professor in the School for Engineering of Matter, Transport and Energy at Arizona State University. His team designs laboratory experiments to identify and measure fundamental turbulence behavior relevant to aerospace, energy, astrophysics, maritime and atmospheric sciences. This is done via application of laser-based (particle image velocimetry, laser-induced fluorescence, etc.) and optical spectroscopic techniques to study wall-bounded turbulent flows, shear-driven turbulent mixing, and reacting flows. He received his PhD in 2017 in theoretical and applied mechanics, and Masters in 2013 in aerospace Engineering from University of Illinois, Urbana-Champaign. He is a recipient of the Stanley Weiss Outstanding Dissertation Award (2017), RISE Fellowship (2012), and Merit Scholarship for Academic Excellence (2006). He was previous a research fellow at Indian Institute of Science and Jawaharlal Nehru Center for Advanced Scientific Research at Bangalore.