ABSTRACT
The basic principles that apply to the analysis and solution of flow problems include the conservation of mass, energy, and momentum, in addition to appropriate transport relations for these conserved quantities. Energy can take a wide variety of forms, such as internal, mechanical, work, kinetic, potential, surface, electrostatic, electromagnetic, and nuclear energy. Also, for nuclear reactions or velocities approaching the speed of light, the interconversion of mass and energy can be significant. An infinitesimal change in internal energy is an exact differential and is a unique function of temperature and pressure. In the foregoing equations, people assumed that the fluid velocity at a given point in the system is the same for all fluid elements at a given cross section in the flow stream. However, this is not true in conduits, because the fluid velocity is zero at a stationary boundary or wall and increases with the distance from the wall.
