Two-phase flow is **two-phase flow is** a fundamental concept and a significant research area within fluid mechanics and thermodynamics concerned with the simultaneous movement of two distinct phases of matter, such as liquid and gas, liquid and solid, or gas and solid. This field investigates the complex interactions, interface dynamics, heat and mass transfer, and flow pattern transitions between the phases, which are critical for understanding and designing systems across diverse engineering and scientific disciplines, including energy systems, chemical processing, and environmental applications.