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