{HEAD ~ Stable operations} have been observed with {TAIL ~ a maximum gas holdup} as high as 0.72 
observed with
{ HEAD ~ Stable operations } have been observed with { TAIL ~ a maximum gas holdup } as high as 0.72
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH