ABSTRACT
Fluid flow touches every aspect of engineering, from industrial processing to research. This chapter presents a perspective of flowmeters by classifying flow measurements as "direct" and "indirect". It discusses Reynolds number, viscosity, laminar flow, and turbulent flow of incompressible fluids. Flow measurement by a weighing or volumetric method removes the fluid from a system and integrates the flow rate over a specific period. The procedure is basic and conceptually simple, but it is not always convenient for field applications. Flow visualization utilizes the flow stream itself for a qualitative and/or quantitative measurement of a flow field. Sonic or ultrasound flowmeters are applicable for pipe lines and open channels. The accuracy depends on the installation, operating conditions, and measuring technique. A laser velocimeter utilizes a frequency shift due to the scattering of a laser beam to measure local fluid velocities. It is suitable for measurements in liquids and gases.
