Control Volume
The flow rate of any quantity into or out of a control volume depends on the flow velocity relative to the control surface, and thus it is essential to know if the control volume remains at rest during flow or if it moves
- Many flow systems involve stationary hardware firmly fixed to a stationary surface,
and such systems are best analyzed using fixed control volumes
- When analyzing flow systems that are moving or deforming,
it is usually more convenient to allow the
control volume to move
or deform
1Fluid Mechanics: Fundamentals and Applications Fourth Edition. Çengel and J. M. Cimbala, McGraw-Hill, New York (2018).