b) means for providing {TAIL ~ a first fluid stream} within said conduit together with {HEAD ~ a second fluid stream} within said conduit 
b ) means for providing { TAIL ~ a first fluid stream } within said conduit together with { HEAD ~ a second fluid stream } within said conduit
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH