Fluid mechanics is the study of how fluids move and the forces on them.Fluid mechanics can be divided into fluid statics, the study of fluids at rest, and fluid dynamics, the study of fluids in motion.
In fluid mechanics, we assume that a fluid is a continuum by ignoring the discontinuity, which molecules and an atom show.
The basic fluid mechanics principles are the continuity equation (i.e. conservation of mass), the momentum principle (or conservation of momentum) and the energy equation.