By observing the changing values of void fraction and liquid density, {HEAD ~ an operator} may observe {TAIL ~ effects} of transient or abrupt changes in the fluid flow 
observe
By observing the changing values of void fraction and liquid density , { HEAD ~ an operator } may observe { TAIL ~ effects } of transient or abrupt changes in the fluid flow
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH