Physics and control of surface-piercing turbulent wake flow
University of Iowa
Abstract
Turbulent free-surface wakes generated by surface-piercing bodies during transient maneuvers represent a technically complex and operationally critical domain in naval hydrodynamics. The unsteady transport of mass, momentum, and energy across the dynamic air–water interface gives rise to highly anisotropic, vortical flows characterized by inherent instabilities that significantly impact the performance and safety of naval platforms. In this study, we characterize the high unsteady and 3D turbulent wake flows of representative surface-piercing bluff bodies using a combination of qualitative and quantitative techniques, including fluorescent dye visualization, synchronized multi-plane Particle Image velocimetry (PIV), and volumetric 3D defocusing PIV. It was found that free-surface wake flows are stabilized at high Froude numbers, with the canonical vortex shedding process suppressed. Consequently, the near-surface wake exhibits reduced mixing and momentum transfer process. In addition, the shedding vortices exhibit a strong spatio-temporal misalignment, causing depth-varying dynamic loadings on the surface-piercing structure. Based on the discoveries, we apply surface-distributed fluid actuators to stabilize the coupled fluid–structure system. The finding results lay the foundation for high-fidelity modeling of anisotropic turbulent shear flows and future intelligent naval systems.
About the speaker
Dr. Cong Wang is currently assistant professor in the Department of Mechanical Engineering at the University of Iowa. Before joining the University of Iowa, he was postdoc associate and research scientist at Caltech. Dr. Wang received his B.Eng. degree in Engineering Science from the National University of Singapore in 2013, and his M.S. and Ph.D. degrees in Aeronautics from Caltech in 2014 and 2019. His current research interests lie in the general areas of physics and control of turbulent multi-phase flow, as well as developing advanced flow diagnosis techniques. He is a recipient of the Ernest E. Sechler Memorial Award in Aeronautics in 2018 and the Donald Coles Prize in Aeronautics in 2019 from Caltech.
