Project Overview: At the ocean interface, surface waves and the resulting generation of turbulence, airflow separation, breaking events, spray, and bubbles regulate momentum and scalar transfers between the atmosphere and ocean and, thus, are fundamental in shaping sea states and weather patterns. Despite their importance and direct impacts on human life, many aspects of air-sea interactions remain poorly understood. In order to improve the predictive abilities of weather and climate models, it is essential to understand fundamental processes that couple surface waves with turbulent flows above and below the ocean surface. In this research avenue, we focus on developing sea-state-dependent parameterizations of sea-surface drag, turbulence structures, and air-sea fluxes using data-driven models. This project integrates laboratory measurements of wind-wave interactions with high-fidelity simulations and digital twin modeling to advance our predictive capabilities of air-sea interaction processes. This research is, in part, in collaboration with Dr. Marco Giometto and Dr. Christopher Zappa at Columbia University.

Funding: National Science Foundation CBET-2404368.

Project Overview: Marine renewable energy is integral in mitigating climate change and reducing reliance on fossil fuels. Offshore wind energy, in particular, has grown significantly due to its potential and advantages over its onshore counterpart. However, the presence of surface waves and currents in offshore environments significantly affects offshore wind turbines (OWTs), posing challenges to their design and operation. In fact, dynamic loads from surface waves lead to fatigue, reduce power generation efficiency, and compromise the structural resistance of OWTs. Thus, understanding the impacts of ocean waves is crucial for optimizing the performance of OWTs and ensuring their long-term sustainability. At the FDT lab, we study the interactions between OWTs and surface waves/currents to enhance their performance. To that end, we focus on wave dynamics, including generation, propagation, and breaking, and investigate the impact of wave-induced loads on the structural integrity and fatigue life of OWT components subjected to various wind-wave conditions. This multidisciplinary effort involves close collaboration with the Wind Energy Center at UT Dallas (UTD Wind).

Funding: UT Dallas SPIRe–Sustainability Program.

Project Overview: Hurricanes account for a significant portion of damage, injury, and loss of life that is attributed to natural hazards and are the costliest natural disasters in the US. To date, considerable uncertainties remain on the air-sea interaction processes under hurricane wind conditions, affecting wind loads on off-shore and on-shore structures. These uncertainties partially stem from limitations of field/laboratory measurements and numerical simulations that are incapable of providing a complete picture of turbulent flow fields. In fact, the current understanding of air-sea interaction processes, even in low-moderate wind conditions, is rather inadequate. This project combines recently developed direct numerical and large-eddy simulation frameworks with measurements to examine the turbulence structure and further elucidate the fundamental mechanisms responsible for air-sea exchanges of momentum, energy, heat, and moisture in hurricane boundary layer flows. The results from this research will provide significant insights into the small-scale dynamics of hurricanes and contribute to a range of applications, spanning from urban resilience to climate change.

Funding: National Science Foundation (NSF) sub-awarded through Computing Research Association (CRA), CIF2020-CU-64.

Project Overview: Surface wave breaking is a complex two-phase flow phenomenon that plays an integral role in coupling the atmosphere and ocean by generating wave-breaking-induced turbulence, entraining air bubbles into the ocean, and ejecting sea spray into the atmosphere. These small-scale processes largely influence the air-sea exchanges of mass, momentum, and energy across the water interface. These fluxes, in turn, affect sea state, weather patterns, and climate and are fundamental components of atmospheric-oceanic models. In this project, we explore the details of wave-breaking dynamics through experimental measurements and numerical simulations. Specifically, the geometric and kinematic breaking criteria are examined, including the steepness associated with incipient wave breaking, the crest-front steepness, the horizontal crest particle velocity, the wave phase speed, and the wave-energy growth rate. Simulations are performed using the Basilisk flow solver that has been extensively validated for multiphase flows with complex interfacial geometries.

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