Two Phase-Flow and Phase-Change: Experiments, Simulations and Modeling

Two-phase flows lie at the core of many natural processes and industrial applications. Predicting bubble nucleation, growth, and interactions is highly challenging due to the wide range of scales involved, from system-level to Kolmogorov turbulence and molecular interfaces, making experimental and numerical studies of two-phase flows particularly complex. On the experimental side, challenges stem from intricate carrier–dispersed phase interactions and background turbulence, and the small spatial and temporal time scales involved in the nucleation and growth of bubbles, necessitating precise, non-intrusive diagnostics such as particle image velocimetry, X-ray radiography/tomography, and high-resolution wall measurement techniques, e.g., infrared thermometry and phase detection. On the numerical side, simulations demand advanced methods to capture interface dynamics (e.g., volume of fluid, level-set, phase-field) in boiling, condensation, and other heat/ mass transfer phenomena. Resolving the full spectrum of spatial and temporal scales requires large grid resolutions and highly efficient solvers capable of leveraging GPU-accelerated high-performance computing. This course presents the latest developments in experimental and numerical techniques for probing the fundamental physics of two-phase turbulent flows, with a focus on boiling heat transfer. Participants will explore state-of-the-art approaches, assess their applicability, strengths, and limitations, and learn strategies for combining methods to improve physical insight. Illustrative examples drawn from the lecturers’ research across thermal engineering and fluid mechanics will showcase these techniques in action. Special emphasis will be placed on advances in high-fidelity simulations and cutting-edge diagnostics, highlighting their role in addressing long-standing challenges in the field. Open questions and future directions will also be critically discussed. By the end of the course, participants will be able to evaluate the capabilities, limitations, and reliability of the methods presented, equipping them with the tools to critically assess data and select appropriate approaches for their own research on two-phase turbulent flows.