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