Turbulence and water waves are classical fluid mechanics problems, and their interactions have many geophysical, environmental, and engineering applications. In this talk, I will present our recent work on the study of the effects of surface waves on the turbulence in water, with a focus on a phenomenon called Langmuir circulations, which are counter-rotating vortex pairs in water caused by the interaction between the wind-driven shear flow and water waves. Using direct numerical and large-eddy simulations, we investigated the modulation effect of the coherent structure of Langmuir circulations on the turbulent boundary layer at the bottom of shallow water. To overcome the limitations of previous studies using simplified models and parameterizations, we further developed a new high-fidelity computational framework to directly capture the wave effects on Langmuir turbulence near the water surface. Our results provided, for the first time, direct numerical support to the Craik-Leibovich theory on its prediction of vortex dynamics. We also discovered a correlation mechanism between wave orbital straining and the variation of turbulence Reynolds stress and developed an efficacious model for this mechanism.
About the Speaker
Professor Lian Shen earned his Bachelor’s Degree in Mechanical Engineering from University of Science and Technology of China in 1993, and Doctor of Science Degree in Fluid Mechanics from Massachusetts Institute of Technology in 2001. He currently holds the position of Kenneth T. Whitby Professor in the Department of Mechanical Engineering at University of Minnesota. He also serves as the director of the St. Anthony Falls Laboratory. Professor Shen’s research interests include computational fluid dynamics, turbulence, water waves, environmental and geophysical fluid flows, and renewable energy.
Host: Professor Leonardo Chamorro