Principles and pitfalls of flow assessment by Doppler ultrasound [in diagnostic medicine and NDT]

A number of techniques have been cited for the analysis of pulsatile flow, and of flow in embedded vessels of unknown geometry. Movement detection, and the repetition rate of cyclic processes can also be monitored with Doppler ultrasound. The accurate estimation of flow is not always possible due to the limitations outlined, but waveform analysis may of itself be helpful in understanding the behaviour of a system. These methods may well be of use in NDT to considerably extend the range of ultrasound measuring devices from the transit time flowmeter. The possibility of using Doppler colour flow mapping to visualise fluid velocity distributions is described; detailed mapping of flows in closed containers, without any disturbance of that flow by the instrumentation, has promise in both industrial measurement and research