Seminar "Wind-Generated Waves in the Laboratory: Turbulent Flow Fields and Interfacial Stresses" by Prof. Chang

Title:  Wind-Generated Waves in the Laboratory: Turbulent Flow Fields and Interfacial Stresses

Presenter:  Kuang-An Chang

Abstract:  This talk presents an experimental investigation of turbulent flow over wind-generated water waves conducted in a laboratory wind-wave flume. Experiments were carried out under three free-stream wind speeds over a short fetch, corresponding to young wave conditions. Instantaneous velocity fields above the water surface were measured using particle image velocimetry (PIV). The velocity fields were decomposed into mean, wave-induced, and turbulent components. The wave field was primarily dissipated through capillary and microscale breaking waves. Turbulent dissipation rates above the water surface were estimated from the resolved spatial gradients of the instantaneous velocities, with time-averaged values calibrated against dissipation rates derived from one-dimensional velocity spectra in the temporal domain. Finally, the turbulent kinetic energy (TKE) budget – accounting for production, dissipation, advection, and turbulent transport – was analyzed and presented.  Flow beneath the free surface and interfacial stresses at the air-water interface will also be discussed.

Bio:  Kuang-An Chang is a Professor in the Zachry Department of Civil & Environmental Engineering at Texas A&M University, with a joint appointment in the Department of Ocean Engineering. He received his BS from National Taiwan University in 1991 and his MS and PhD from Cornell University in 1994 and 1999, respectively. After completing a one-year postdoc at Cornell, he joined the Texas A&M faculty in 2000. His research primarily focuses on physical modeling using optics and imaging-based, non-intrusive measurement techniques for quantitative flow visualization, with applications in coastal and ocean environments.