Vortices generate fluid oscillations that are detected when they pass through the beam and induce {HEAD ~ phase changes} representative of {TAIL ~ fluid flow rate} 
Vortices generate fluid oscillations that are detected when they pass through the beam and induce { HEAD ~ phase changes } representative of { TAIL ~ fluid flow rate }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL