By offsetting the pedestals in the second row relative to the pedestals in the first row positioned upstream from the second row and by alternating {HEAD ~ the protrusions} from {TAIL ~ the inner wall} to the outer wall, or vice versa, a spiral flow of gas may be created in the cavity 
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By offsetting the pedestals in the second row relative to the pedestals in the first row positioned upstream from the second row and by alternating { HEAD ~ the protrusions } from { TAIL ~ the inner wall } to the outer wall , or vice versa , a spiral flow of gas may be created in the cavity
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH