1) Fluid mechanics 2) Hydraulics 
• (n.) The branch of science which relates to the pressure and equilibrium of nonelastic fluids, as water, mercury, etc.; the principles of statics applied to water and other liquids.
(from the article `fluid mechanics`) It is common knowledge that the pressure of the atmosphere (about 105 newtons per square metre) is due to the weight of air above the Earth`s ... The basis of naval architecture is found in Archimedes` principle, which states that the weight of a statically floating body must equal the weight ... ...
The mathematical study of forces and pressures in liquids or at rest.
(hi″dro-stat´iks) the science of equilibrium of fluids.
Hy`dro·stat'ics noun [ Confer French hydrostatique .] (Physics) The branch of science which relates to the pressure and equilibrium of nonelastic fluids, as water, mercury, etc.; the principles of statics applied to water and other liquids. 
Hydrostatics is that part of the general science of hydrodynamics that deals with the application of forces to fluids at rest. Among the chief principles of hydrostatics may be mentioned the following:
[n] - study of the mechanical properties of fluids that are not in motion
hydrostatics 1. The science of pressures and levels in water and hence in liquids generally. 2. The study of liquids at rest and the forces exerted on them or by them. 3. The study of liquids at rest as well as the forces and pressures associated with them.
That part of the science of mechanics which deals with the equilibrium of stationary bodies immersed in water or on its surface.
noun study of the mechanical properties of fluids that are not in motion
Branch of statics dealing with fluids in equilibrium – that is, in a static condition. Practical applications include shipbuilding and dam design
the branch of hydrodynamics that deals with the statics of fluids, usually confined to the equilibrium and pressure of liquids.