Thermal-hydraulics is the study of the behavior of fluids under the influence of heat. It combines principles from both thermodynamics and fluid mechanics to analyze how heat transfer affects fluid flow. This field is essential in various applications, including power generation, refrigeration, and chemical processing. In nuclear engineering, thermal-hydraulics plays a crucial role in ensuring the safe and efficient operation of reactors. It helps engineers design systems that manage heat removal and maintain optimal temperatures, preventing overheating and ensuring the stability of the reactor core.