Abstract:
This talk presents a comprehensive overview of recent advancements in high-fidelity numerical simulations of two-phase flows, transitioning from isothermal Taylor bubble dynamics in counter-current flows to research in boiling phenomena. Initially, a detailed investigation into Taylor bubbles, characterized by large gas pockets separated by liquid slugs, is discussed. This research employs a dual approach that couples advanced numerical simulations with state-of-the-art experimental techniques. The analysis covers Taylor bubbles within air-water mixtures under transitional (Re=1400) and fully turbulent (Re=5600) flow regimes and highlights key differences in bubble shape and interfacial dynamics, such as the formation of asymmetric, bullet-train-like structures in turbulent conditions and axisymmetric forms in transitional flows. Advanced image reconstruction techniques were utilized to identify and track disturbance waves across bubble interfaces, which enhances the understanding of Taylor bubble breakup mechanisms.
Building upon this foundation, the second part of the presentation transitions to ongoing research into boiling flows. The development of phase-change simulation techniques applicable to complex, realistic geometries using unstructured meshes will be discussed. Addressing a significant challenge in computational fluid dynamics, a novel algebraic-geometric Volume-of-Fluid (VoF) method integrated within an in-house CFD framework is introduced. Validation against classic benchmarks—including Stefan, Sucking, and Scriven problems—confirms the accuracy and scalability of the developed methodology and showcases its potential for detailed simulations of boiling phenomena.
Laboratory for Simulation and Modeling