Steady flow of incompressible fluids
Fluid mechanics is concerned with the study of forces and movements of liquids and gases. Both substances are continua whose elements can easily move against each other. They are grouped together under the term ‘fluid’.
Liquids are incompressible. In technical fields of application of fluid mechanics, incompressibility is also assumed for gases as long as the flow velocity remains below Mach 0,3. Based on air at 20°C this limiting value corresponds to a velocity of approximately 100m/s and the change in density is roughly 4%. It is therefore broadly possible to treat liquid and gas flows with common fundamental principles in fluid mechanics.
Steady and transient flow
Steady flow: the velocity of a fluid particle changes with the position: v=f(s).
Transient flow: the velocity of a fluid particle changes with the time and the position: v=f(s,t).
Transient flows occur during discharge processes, during startup and shutdown processes of turbomachines or in the case of fluid oscillations and water hammer processes
To get a better understanding about the different states of fluids, take a look at the following video.
Velocity profile in fully developed flow
Pressure losses in straight pipes
Pressure losses in pipe fittings
enlargement/constriction/change of direction
segment bends /pipe angles
Losses in single-strand and multi-strand pipe systems
Flow rate metrology: representation of the common industry measuring methods
Cavitation effects in industrial piping systems: formation and consequences
Special emphasis on technical issues
subcritical and supercritical flow