Because of {HEAD ~ the difference} in {TAIL ~ the material densities}, melt will be accumulated at the bottom of the vessel 
in
Because of { HEAD ~ the difference } in { TAIL ~ the material densities } , melt will be accumulated at the bottom of the vessel
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH