Acoustic Flowmeter:
Average Axial Velocity of Water Flow:

Acoustic Path Length between Transducer Faces:

Angle between Acoustic Path and the Pipe's Longitudinal Axis:

Acoustic Signal Downstream Travel Time:

Acoustic Signal Upstream Travel Time:

where,
V
a = Average Axial Velocity of Water Flow,
L = Acoustic Path Length between Transducer Faces,
θ = Angle between Acoustic Path and the Pipe's Longitudinal Axis,
t
d = Acoustic Signal Downstream Travel Time,
t
u = Acoustic Signal Upstream Travel Time.