Dr. Yongyun Hwang

My research is defined at interface between applied mathematics and engineering. I enjoy discovering new and fundamental flow physics from simplified problems using hydrodynamic stability theories, modern control theories, variational calculus, and scientific computing. My research interests are rather broadly defined and cover

• Instabilities, transition and turbulence
• Pattern formation in biological fluid systems
• Continuum modelling of active fluids
• Optimization & control of fluid flows
• Direct & large eddy simulations

For further details, see below. If you are interested in working any of the following projects, please do not hesitated to e-mail me.

Significant progress has been made in understanding wall-bounded turbulent flows for the last decade. From theoretical perspective, introduction of dynamical system approaches have initiated new view on the dynamics of coherent structures, while experimentalists have discovered new types of coherent structures. The current work is to devoted to establishing a complete and consistent dynamical description on the coherent structures in the near-wall turbulence by combining hydrodynamical stability theory, dynamical system theory and well-known Townsend's attached eddy hypothesis.

The wake behind a bluff body is an important canonical flow for engineering applications, as vortex shedding in wakes is a main source of drag, structural vibration and aeroacoustic noise.  My current research interest is to understand a bluff-body wake in a stratified medium. In particular, the research is aimed at studying interaction of vortex shedding with internal gravity wave generated by the density stretification. 

Microorganisms are present in almost every part of temperate aqueous environments, and they play a critical role in pathogenic infection, digestion, reproduction, and food chains in the oceans. Many swimming microorganisms often exhibit collective behaviors, and it often originates from interaction of the microorganisms' motility with surrounding fluid flows. The focus of the current research is aimed at understanding how these collective dynamics of the swimming microorganisms (particularly biflagallate algae, e.g. Chlamydomonas) interact with instabilities in shear flows. Another important recent research is to find efficient mixing startegies of the microorganism suspensions using optimal control theory for biofuel harvesting.