[Speaker]

Prof. Jae Sung Park
Richard L. McNeel Associate Professor of Engineering
Mechanical & Materials Engineering
University of Nebraska-Lincoln

[Abstract]

This seminar will start by introducing diverse fluid-mechanics research conducted in the Park research group at Nebraska. I will then discuss the application of dynamical systems theory to wall-bounded fluid flows. In particular, I will talk about the discovery of the so-called exact coherent states, specifically nonlinear traveling-wave solutions to the Navier–Stokes equations. These solutions are unstable saddle points in state space, where the time evolution of a fluid flow is a dynamical trajectory wandering around them. Several new classes of exact coherent states with different symmetries are computed, and their connections to laminar-to-turbulent transition and turbulent dynamics will be discussed. Lastly, I will discuss the roles of exact coherent states in flow control for transition to turbulence and turbulent drag reduction.