"Unraveling a complex multiphase flow problem in oceanic environments using simulations and analysis"

Abstract:  Multiphase flows play a central role in various applications, including additive manufacturing processes, biophysical systems, energy conversion/storage, and environmental flows. Numerical simulations can enhance our understanding of such flows and aid in optimization, design, and control. In this talk, I briefly introduce a novel numerical method for simulating multiphase flows involving complex multi-physics effects. I then focus on a practical example of significant interest whereby I use simulations and analysis to enhance our predictive understanding of micro-bubble formation in oceanic environments. Micro-bubbles have a long residence time under the free surface, influencing heat and mass transfer and the traceability of ship vessels in oceans. The formation mechanism of such bubbles was unknown before the work presented here due to the microscopic scales involved and the lack of quantitative data related to the micro-bubbles. I reveal the intricate mechanisms involved in the multi-stage, multi-scale, multiphase flow problem of micro-bubble entrapment. Most notably, I present multiple instances of simulations providing proof for hypotheses and enabling the scientific discovery of physical phenomena and scaling laws. I explain how my findings can be used as subgrid-scale models to capture micro-bubble generation in large-scale simulations of turbulent breaking waves. Lastly, I outline similarities between this complex flow problem and the phenomenon responsible for generating aerosols in human lungs during breathing, known as the Bronchiole Fluid Film Burst (BFFB) mechanism.