What is defined as a control volume in computational fluid dynamics (CFD)?

In computational fluid dynamics (CFD), a control volume is defined as a volume through which fluid flows. This concept is foundational in the study of fluid mechanics, as it allows engineers and researchers to apply the principles of mass, momentum, and energy conservation within a defined space.

Control volumes can vary in size and shape, and they are used to analyze how fluid properties change as they move through space. By selecting a control volume, one can derive governing equations that describe the behavior of the fluid, including velocity, pressure, and density changes. This approach effectively aids in simulating and predicting flow characteristics in various applications, from aerodynamics to hydraulics.

This definition distinguishes the concept of a control volume from others, such as a specific area with fixed boundaries, which does not account for the dynamic interaction between fluid and volume. Control volumes are also not limited to regions devoid of fluid flow or theoretical constructs without physical meaning; rather, they are practical tools used in real-world fluid dynamics analysis.