Editing Doppler effect (section)

===Flow measurement===
Instruments such as the [[laser Doppler velocimetry|laser Doppler velocimeter]] (LDV), and [[acoustic Doppler velocimetry|acoustic Doppler velocimeter]] (ADV) have been developed to measure velocities in a fluid flow. The LDV emits a light beam and the ADV emits an ultrasonic acoustic burst, and measure the Doppler shift in wavelengths of reflections from particles moving with the flow. The actual flow is computed as a function of the water velocity and phase. This technique allows non-intrusive flow measurements, at high precision and high frequency.