Flow measurement is the quantification of bulk fluid movement. Flow
can be measured in a variety of ways. Positive-displacement flow
meters accumulate a fixed volume of fluid and then count the number
of times the volume is filled to measure flow. Other flow
measurement methods rely on forces produced by the flowing stream
as it overcomes a known constriction, to indirectly calculate flow.
Flow may be measured by measuring the velocity of fluid over a
known area.
