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Shock-induced phenomena in turbulent flows through numerical simulation and diagnostics

Event Type: 
Date and Time: 
Friday, September 25, 2020 - 16:30
Event Sponsor: 
Parviz Moin, Director of Center for Turbulence Research
Professor Ivan Bermejo-Moreno

Shock-induced scalar mixing and ignition under canonical shock-turbulence interactions (STI) will be considered first, by means of Direct Numerical Simulation in 3D and 2D, respectively. The effects of relevant physical parameters (shock and turbulence Mach numbers, and Reynolds number) will be highlighted on statistical changes along the shock-normal direction of scalar variance and dissipation-rate budgets, flow topology, and alignments of the scalar gradient with vorticity and strain-rate eigendirections. Shock-induced scalar mixing will also be addressed by tracking the downstream evolution of the geometry and physics of scalar structures initialized with a well-defined shape as they are transported and diffused by the background turbulence in STI, and compared with decaying homogeneous isotropic turbulence.

Flow-structure interactions of shock waves reflecting off turbulent boundary layers that develop along flexible walls will be addressed next, comparing results from ongoing numerical simulations with prior wind tunnel experiments. The calculations couple wall-modeled large-eddy simulation for the fluid flow, using an Arbitrary Lagrangian-Eulerian formulation, with an elastic solid structural solver that accounts for geometric nonlinearities, and a mesh deformation module based on a spring-system analogy. Strong shock/boundary-layer interactions resulting in mean flow separation and low-frequency unsteadiness that can interact with the natural frequencies of the structure will be emphasized.

Ivan Bermejo-Moreno received his Ph.D. in aeronautics in 2008 from the California Institute of Technology. Afterwards, he held a postdoctoral research fellowship at the Center for Turbulence Research, Stanford University/NASA Ames Research Center from 2009 to 2014. He joined the Aerospace and Mechanical Engineering Department at the University of Southern California in 2015. His research combines numerical methods, physical modeling and high-performance computing for the simulation and analysis of turbulent fluid flows involving multi-physics phenomena. He is a recipient of the Fulbright Fellowship, the Rolf D. Buhler Memorial Award, the William F. Ballhaus Prize and the Hans G. Hornung Prize.