The accelerated positively charged ions accelerate low energy air within lower regions of {TAIL ~ a boundary layer} over the ducted surfaces bounding {HEAD ~ the ducted fluid flow} 
The accelerated positively charged ions accelerate low energy air within lower regions of { TAIL ~ a boundary layer } over the ducted surfaces bounding { HEAD ~ the ducted fluid flow }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD