Fluid Dynamics provides methods for studying the evolution of stars, ocean currents, weather patterns, plate tectonics and even blood circulation. It is the branch of applied science that is concerned with the movement of liquids and gases. Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation. It is one of two branches of fluid mechanics, which is the study of fluids and how forces affect them.