each element thereby providing {HEAD ~ a number} of {TAIL ~ adjacent pointwise boundary layer interruptions} corresponding to the number of blade like members thereof, 
each element thereby providing { HEAD ~ a number } of { TAIL ~ adjacent pointwise boundary layer interruptions } corresponding to the number of blade like members thereof ,
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH