1) Hydrodynamics 
• (n.) That branch of physics which treats of the mechanics of liquids, or of their laws of equilibrium and of motion.
Hy`dro·me·chan'ics noun [ Hydro- , 1 + mechanics .] That branch of physics which treats of the mechanics of liquids, or of their laws of equilibrium and of motion. 
hydromechanics 1. The study of the mechanics of fluids or the laws of equilibrium and motion concerning fluids. 2. The area of fluid dynamics that is concerned with the study of liquids.
hydrodynamics.