Fluid dynamics is "the branch of engineering that's concerned with the movement of liquids and gases," consistent with the American Heritage Dictionary. Fluid dynamics is one among two branches of hydraulics , which is that the study of fluids and the way forces affect them. (The other branch is fluid statics, which deals with fluids at rest.)
Scientists across several fields study fluid dynamics. Fluid dynamics provides methods for studying the evolution of stars, ocean currents, weather patterns, tectonics and even blood circulation. Some important technological applications of fluid dynamics include rocket engines, wind turbines, oil pipelines and air con systems.
The movement of liquids and gases is usually mentioned as "flow," an idea that describes how fluids behave and the way they interact with their surrounding environment — for instance , water moving through a channel or pipe, or over a surface. Flow are often either steady or unsteady