A popular way to mitigate this problem is to use multiple sensor pairs, sending acoustic signals
along multiple paths through the fluid (i.e. a multipath ultrasonic flowmeter), and to average the
resulting velocity measurements. Dual-beam flowmeters have been in use for well over a decade at
the time of this writing (2009), and one manufacturer even has a five beam ultrasonic flowmeter
model which they claim maintains an accuracy of +/- 0.15% through the laminar-to-turbulent flow
regime transition. A simplified illustration of a Daniel four-beam (or four “chord”) ultrasonic
flowmeter is shown here: