In the flow of fluid in place a blunt cylindrical body, it will have on both sides of the lower reaches of the cylinder are two of the vortex, with a vortex of the cylinder and around the lower reaches of the fluid will have a regular vibration, the vibration Frequency and flow of correspondence between existence.

Constraints in the swirl through the expansion of the time, will have a swirl into the phenomenon, a fluid vibration, the vibration frequency and velocity is directly proportional relationship.

In addition, the wall jet components made of fluid oscillator, and may also have a flow rate proportional to the fluid vibration.

Measurement of the frequency of fluid flow meter to measure, known as the fluid vibration flowmeter.

Vibration fluid flow meter is developed in the late 60's a relatively new flow measurement technology, it has the following characteristics: availability and flow in direct proportion to the frequency output signals; tested fluid vibration in itself is no mechanical moving parts ; Almost from fluid composition, density, viscosity, pressure and other factors; flowmeter compared with the expenditure of its small pressure loss, such as range than the width. Therefore, the measurement method more and more people's attention, is in the process of continuous development of sound.