Flow characteristics and you will see that at very low speed edge at the middle with speed higher than pure eof therefore combine opposite flow need more volts to trap particles.
The flow is seen that the margins are very low at the middle speeds are faster than pure eof combine opposite flow, so it requires more volts to trap particles.
Flow characteristics shows that the edge is very low speed at the middle has higher speed pure EOF so combine opposite flow It must be used volts more to trap particles