Water flowing through the intake grate flows through {HEAD ~ the concavity} in a laminar flow and encounters {TAIL ~ no obstacles} other than the elongate drive shaft before encountering the impeller 
Water flowing through the intake grate flows through { HEAD ~ the concavity } in a laminar flow and encounters { TAIL ~ no obstacles } other than the elongate drive shaft before encountering the impeller
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH