Using polynomial regression, {HEAD ~ an empirical relationship} can be found between {TAIL ~ the density} and pressure drop 
found between
Using polynomial regression , { HEAD ~ an empirical relationship } can be found between { TAIL ~ the density } and pressure drop
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH