The melt circulation through the conduits is caused by the difference in the levels and {HEAD ~ densities} of {TAIL ~ the melt} in these vessels 
of
The melt circulation through the conduits is caused by the difference in the levels and { HEAD ~ densities } of { TAIL ~ the melt } in these vessels
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH