Pressure bubble myth
Graviman
That is correct, according to Impuls theory / Bernoulli, the wake tunnel below the MR in OGE contracts and will progressively half surface down stream (so square root for diameter), whilst induction doubles from vi to 2vi with the corresponding static pressure drop starting from below the rotor
In IGE the geometry is different, very turbulent, so too complex, so the whole argument starts upstream from the rotor (once we agreed upon the effects on trust and vi-IGE) and continues down stream to just below the rotor up to that point where the wake stops OGE-like contracting because of the ground proximity. I did not make any prognosis on the speeds/pressures from there on.
This is why measurements should be reasonably close to the MR, but not too close to reduce the "loadspeaker" pulses (a few feet i would say) and increase setup safety.
d3