MAE Seminar: On the Physics and Simulation of Turbulence

Abstract: The phenomenon of turbulence in fluid flows is a paradigmatic nonlinear multiscale dynamical system in classical physics with important implications for a wide range of natural and engineered flows. Brute force simulations of many societally relevant turbulent flows are far out of reach even on today's world-class supercomputers, and this will remain the case for the foreseeable future. As a result, turbulence modeling plays a central role in advancing the state-of-the-art for computational fluid dynamics. A promising, and increasingly popular, approach to turbulence modeling is large-eddy simulation (LES). In LES, the large-scale turbulent fluctuations of a given flow are directly resolved and approximate models are constructed to represent the net effects of smaller-scale motions. One of the primary tasks of LES sub-grid scale models is to remove kinetic energy from resolved scales in an accurate manner. In this talk, I will review the scale-wise dynamics of kinetic energy in turbulent flows as it relates to modeling and simulation. A new perspective on the underlying theory of LES will be introduced, advancing our fundamental understanding of turbulence physics and suggesting a new framework for extending the effectiveness of LES to more complex (e.g., multiphase) turbulent flows.

Bio: Perry Johnson earned his Ph.D. in 2017 from Johns Hopkins University, where his work on velocity gradient dynamics in turbulence won the Corrsin-Kovasznay award. He was then a postdoctoral fellow at the Center for Turbulence Research at Stanford University for three years, working on various topics related to turbulence theory, multiphase flows and boundary layers. In 2020, he joined the UCI MAE department as an assistant professor. His research on the energy cascade in turbulence was recently featured in Physics Today.