In a fluid handling apparatus {HEAD ~ a bladed interrupter structure} adapted for {TAIL ~ pointwise interruption} of the boundary layer of a fluid flow at an apparatus surface or surfaces of the apparatus immediately adjacent to the interrupter structure, the said structure comprising: 
adapted for
In a fluid handling apparatus { HEAD ~ a bladed interrupter structure } adapted for { TAIL ~ pointwise interruption } of the boundary layer of a fluid flow at an apparatus surface or surfaces of the apparatus immediately adjacent to the interrupter structure , the said structure comprising :
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