fundamental equations of hydrodynamics

The equations of motion, the equation of continuity, the energy equation, the equation of state, and the equation of continuity for water substance, considered together as a closed system of equations.

A simplified physical model can dispense with certain of these equations without sacrificing completeness; for example, in two-dimensional homogeneous incompressible flow, kinetic energy is the only form of energy, and the equations of motion and continuity form a closed system.