When fluids pass over an object, oscillations in the fluid flow occurs. These oscillations are called vortices. There are many examples of vortices in nature. For example, you can witness an oscillation in nature when the wind is whistling through tree branches. Another example is a flag waving in the breeze and the waving of the flag is caused by vortices on each side of the flag.
When flow hits an object, called a bluff body or shedder, the flow is separated and travels around the object before continuing downstream. On each side of the object vortex, swirls (vortices) occur that separate at the contact point of the object. The object causes vortex swirls on each side of the object. One side will have high-pressure swirls and the other side will have low-pressure swirls.
The swirls on each side of the object will be out of phase with the other by 180 degrees. Measuring the formation frequency of the vortices on either side of the object will determine the flow rate. Furthermore, the speed of the fluid is directly proportional to the width of the object and the frequency of the vortex.
Vortex meters can measure each form of a fluid, including steam, liquid and gas. For industries needing a cost-effective, low maintenance, reliable method to measure flow, the vortex meter is best. Because it has no moving parts, the vortex meter does not require routine maintenance or cleaning.