{HEAD ~ The apparatus} 1 wherein {TAIL ~ the flow obstruction} comprises a plurality of bluff bodies and the oscillating flow components are produced from vortices shed from the bluff bodies 
{ HEAD ~ The apparatus } 1 wherein { TAIL ~ the flow obstruction } comprises a plurality of bluff bodies and the oscillating flow components are produced from vortices shed from the bluff bodies
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH