Relative motion between {TAIL ~ the liquid mass} and upper and lower case structures generates {HEAD ~ a voltage potential} between the upper and lower cases, representing the relative velocity 
Relative motion between { TAIL ~ the liquid mass } and upper and lower case structures generates { HEAD ~ a voltage potential } between the upper and lower cases , representing the relative velocity
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH