Several such helicoid structures are combined with their radii overlapping, for {HEAD ~ the most effective interception} of {TAIL ~ a certain cross sectional area} of the fluid flow 
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Several such helicoid structures are combined with their radii overlapping , for { HEAD ~ the most effective interception } of { TAIL ~ a certain cross sectional area } of the fluid flow
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH