Control Volume

In thermodynamics, the control volume was stated as a fixed area in space where one studies the masses and energies crossing the boundaries of the area. This idea of a control volume is also very helpful in examining fluid flow troubles. The boundary of a control volume for fluid flow is generally taken as the physical boundary of the portion via which the flow is taking place. The control volume idea is employed in fluid dynamics applications, using the momentum, continuity, and energy principles. Once the control volume and its boundary are establish, the different forms of energy crossing the boundary with the fluid can be dealt with in equation form to resolve the fluid trouble. As fluid flow troubles generally treat a fluid crossing the boundaries of a control volume, the control volume approach is termed to as an "open" system analysis that is similar to the ideas studied in thermodynamics. There are special situations in the nuclear field where fluid does not cross the control boundary. These situations are studied using the "closed" system approach.

Despite of the nature of the flow, all flow cases are found to be subject to the established fundamental laws of nature which engineers have stated in equation form. The conservation of mass and conservation of energy are forever satisfied in fluid troubles, all along with Newton's laws of motion. Additionally, each problem will have physical restrictions, termed to mathematically as boundary conditions that should be satisfied before an answer to the problem will be consistent with the physical outcomes.