The Department of Mechanical, Materials, and Aerospace Engineering presents a 2023–2024 Seminar Series featuring guest speaker Theresa Saxton-Fox, who will give a presentation on “History effects in turbulent boundary layers: spatially and temporally varying pressure gradients.” This seminar will take place on Wednesday, September 13, 2023 in the auditorium (room 104) of the John T. Rettaliata Engineering Center from 3:30–4:30 p.m. This event is open to all graduate students and faculty.
Wall-bounded turbulent flows are ubiquitous in transportation and energy technologies on curving bodies and in unsteady flows. Turbulence is complex even in “canonical” geometries (flat walls, straight pipes, and straight channels) and flow acceleration further complicates its physics. In this talk, we discuss novel experimental facilities that enable the systematic characterization of complex pressure gradient and curvature effects, including variable spatial and temporal history. The experiments are carried out using a variable-positioned ceiling and are measured using time-resolved, planar particle image velocimetry. Statistical results are shown for both statically held and dynamic pressure gradients. History effects (prior pressure gradients imposed upstream of the position of interest) and dynamic effects (a dependence on the rate of pressure gradient imposition) are both observed. The formation of an internal layer due to the spatially varying pressure gradients is identified for stronger but not weaker static pressure gradient variations, yielding distinct downstream boundary layer evolution. The growth rate and vortex activity of the internal layer are reported. Dynamic pressure gradients in the present configuration are observed to lessen the influence of the internal layer.
Theresa Saxton-Fox is an Assistant Professor of Aerospace Engineering at the University of Illinois at Urbana-Champaign. She received her Masters and PhD from Caltech and did her postdoctoral research at Princeton University, prior to starting at the University of Illinois in January 2019. Her work focuses on wall-bounded turbulent flows with particular interests in nonlinear interactions, global unsteadiness, and curvature effects. She was awarded the Centennial prize for best thesis in the Mechanical and Civil Engineering department at Caltech in 2018, the Young Investigator Program award from the Office of Naval Research in 2021, and the College Award for Leadership or Institutional Impact in Diversity, Equity, and Inclusion from the Grainger College of Engineering at the University of Illinois Urbana-Champaign in 2023.