In line. As far as which direction the bubbles flow from the stone that's a matter of whether you bore W/ or across the grain. Flip em upside down and they all look alike ! Fitting a stone within the venturi is like building a ship in a bottle, this coming from a man that's accustomed to working sub-scale.

It makes no difference to me "How" the results are acheived. Only that they are, in a practicle manner.

It is interesting though. Given your background, and experience you could roll up yer sleeves and dive into it ? Bench racing design and theory is the only way to push the envelope. As always your expertise is welcome, and appreciated. HTH. Prof M