{TAIL ~ The cross section} of flow of the tube 20 in this region is given a transition radius R, the size of which in principle depends on the flow inside {HEAD ~ the tube} 20 
{ TAIL ~ The cross section } of flow of the tube 20 in this region is given a transition radius R , the size of which in principle depends on the flow inside { HEAD ~ the tube } 20
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH